PPAR/RXR Regulation of Fatty Acid Metabolism and Fatty Acid omega-Hydroxylase (CYP4) Isozymes: Implications for Prevention of Lipotoxicity in Fatty Liver Disease. PPAR Res. 2009;2009:952734. [PMID: 20300478 PMCID: PMC2840373 DOI: 10.1155/2009/952734]

Unlocking new avenues for neuropsychiatric disease therapy: the emerging potential of Peroxisome proliferator-activated receptors as promising therapeutic targets

RATIONALE

Peroxisome proliferator-activated receptors (PPARs) are transcription factors that regulate various physiological processes such as inflammation, lipid metabolism, and glucose homeostasis. Recent studies suggest that targeting PPARs could be beneficial in treating neuropsychiatric disorders by modulating neuronal function and signaling pathways in the brain. PPAR-α, PPAR-δ, and PPAR-γ have been found to play important roles in cognitive function, neuroinflammation, and neuroprotection. Dysregulation of PPARs has been associated with neuropsychiatric disorders like bipolar disorder, schizophrenia, major depression disorder, and autism spectrum disorder. The limitations and side effects of current treatments have prompted research to target PPARs as a promising novel therapeutic strategy. Preclinical and clinical studies have shown the potential of PPAR agonists and antagonists to improve symptoms associated with these disorders.

OBJECTIVE

This review aims to provide an overview of the current understanding of PPARs in neuropsychiatric disorders, their potential as therapeutic targets, and the challenges and future directions for developing PPAR-based therapies.

METHODS

An extensive literature review of various search engines like PubMed, Medline, Bentham, Scopus, and EMBASE (Elsevier) databases was carried out with the keywords "PPAR, Neuropsychiatric disorders, Oxidative stress, Inflammation, Bipolar Disorder, Schizophrenia, Major depression disorder, Autism spectrum disorder, molecular pathway".

RESULT & CONCLUSION

Although PPARs present a hopeful direction for innovative therapeutic approaches in neuropsychiatric conditions, additional research is required to address obstacles and convert this potential into clinically viable and individualized treatments.

Proteomic and metabolomic analysis of GH deficiency-induced NAFLD in hypopituitarism: insights into oxidative stress

Objective

Individuals with hypopituitarism (HPs) have an increased risk of developing non-alcoholic fatty liver disease (NAFLD)/non-alcoholic steatohepatitis (NASH) due to growth hormone deficiency (GHD). We aimed to investigate the possible mechanisms underlying the relationship between GHD and NAFLD using proteomic and metabolomic insights.

Methods

Serum metabolic alternations were assessed in male HPs using untargeted metabolomics. A rat model of HP was established through hypophysectomy, followed by recombinant human growth hormone (rhGH) intervention. The mechanisms underlying GHD-mediated NAFLD were elucidated through the application of label-free proteomics and phosphorylation proteomics.

Results

Metabolomic analysis revealed that biomarkers of mitochondrial dysfunction and oxidative stress, such as alanine, lactate, and creatine, were significantly elevated in HPs compared to age-matched controls. In rats, hypophysectomy led to marked hepatic steatosis, lipid peroxidation, and reduced glutathione (GSH), which were subsequently modulated by rhGH replacement. Proteomic analysis identified cytochrome P450s, mitochondrial translation elongation, and PPARA activating genes as the major distinguishing pathways in hypophysectomized rats. The processes of fatty acid transport, synthesis, oxidation, and NADP metabolism were tightly described. An enhanced regulation of peroxisome β-oxidation and ω-oxidation, together with a decreased NADPH regeneration, may exacerbate oxidative stress. Phosphoproteome data showed downregulation of JAK2-STAT5B and upregulation of mTOR signaling pathway.

Conclusions

This study identified proteo-metabolomic signatures associated with the development of NAFLD in pituitary GHD. Evidence was found of oxidative stress imbalance resulting from abnormal fatty acid oxidation and NADPH regeneration, highlighting the role of GH deficiency in the development of NAFLD.

The probiotic SLAB51 as agent to counteract BPA toxicity on zebrafish gut microbiota -liver-brain axis

A plethora of studies have so far described the toxic effects of bisphenol A (BPA) on organism health, highlighting the urgent need to find new strategies not only to reduce the presence of this toxicant but also to counteract its adverse effects. In this context, probiotics emerged as a potential tool since they promote organism welfare. Using a multidisciplinary approach, this study explores the effects of SLAB51 dietary administration to counteract BPA toxicity using zebrafish as a model. Adult males and females were maintained under standard conditions (control group; C), exposed for 28 days via the water to an environmental relevant dose of BPA (10 μg/L; BPA), dietary treated with SLAB51 (109 CFU/g of body weight; P) and co-treated with BPA plus SLAB51 (BPA + P). In the gut, exposure to BPA resulted in altered architecture in both males and females, with females also experiencing an increase of pathogenic bacterial species. Co-administration of BPA + P led to the restoration of normal gut architecture, favored beneficial bacteria colonization, and decreased the abundance of pathogenic species. In the liver, male BPA exposure led to steatosis and glycogen depletion, which was partially mitigated by SLAB51 co-administration. In contrast, in females exposed to BPA, the lack of steatosis along with the greater glycogen depletion, suggested an increase in energy demand as supported by the metabolomic phenotype. The analysis of liver metabolites in BPA + P males revealed increased levels of anserine and reduced levels of glutamine, which could lie behind the counteraction of the brain histopathological damage caused by BPA. In BPA + P females, a reduction of retinoic acid was found in the liver, suggesting an increase in retinoids responsible for BPA detoxification. Overall, these results demonstrate that SLAB51 exerts its beneficial effects on the gut microbiota-brain-liver axis through distinct molecular pathways, effectively mitigating the pleiotropic toxicity of BPA.

Revealing curcumin therapeutic targets on SRC, PPARG, MAPK8 and HSP90 as liver cirrhosis therapy based on comprehensive bioinformatic study

Cirrhosis naturally progresses through three stages: compensated, decompensated, and late decompensated, which carry an elevated risk of death. Although curcumin's anti-cirrhosis effects have been studied, underlying mechanism in preventing cirrhosis progression and the correlation between curcumin's action with upregulated genes remains insufficiently explored. In this study, we employed network pharmacology approach to construct a drug-target-disease network through bioinformatics and validate the findings with molecular docking and dynamic simulation. The curcumin-targeted liver cirrhosis network encompassed 54 nodes with 282 edges in protein-protein interactions (PPI) network. By utilizing network centrality analysis, we identified eight crucial genes. KEGG enrichment pathway revealed that these crucial genes are involved in pathway of cancer, endocrine resistance, estrogen signaling, chemical carcinogenesis-receptor activation, lipid metabolism, and atherosclerosis. Notably, these eight genes predominantly participate in cancer-related pathways. Further investigation revealed upregulation of four genes and downregulation of four others in hepatocellular carcinoma patients. These upregulated genes-MAPK8, SRC, PPARG, and HSP90AA1-strongly correlated with reduced survival probability in liver hepatocellular carcinoma patients with survival times approximately under 4000 days (∼11 years). Molecular docking and molecular dynamic results exhibited curcumin's superior binding affinities and stability compared to native ligands of MAPK8, SRC, PPARG, and HSP90AA1 within 50 ns simulations. Moreover, MM-GBSA analysis showed stronger binding energy of curcumin to MAPK8, SRC, and HSP90AA1 than native ligand. In conclusion, this study provides valuable insights into curcumin's potential mechanisms in preventing liver cirrhosis progression, specifically in HCC. These findings offer a theoretical basis for further pharmacological research into anti-HCC effect of curcumin.Communicated by Ramaswamy H. Sarma.

Modulation of mitochondrial activity by sugarcane (Saccharum officinarum L.) top extract and its bioactive polyphenols: a comprehensive transcriptomics analysis in C2C12 myotubes and HepG2 hepatocytes

Age-related mitochondrial dysfunction leads to defects in cellular energy metabolism and oxidative stress defense systems, which can contribute to tissue damage and disease development. Among the key regulators responsible for mitochondrial quality control, peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) is an important target for mitochondrial dysfunction. We have previously reported that bioactive polyphenols extracted from sugarcane top (ST) ethanol extract (STEE) could activate neuronal energy metabolism and increase astrocyte PGC-1α transcript levels. However, their potential impact on the mitochondria activity in muscle and liver cells has not yet been investigated. To address this gap, our current study examined the effects of STEE and its polyphenols on cultured myotubes and hepatocytes in vitro. Rhodamine 123 assay revealed that the treatment with STEE and its polyphenols resulted in an increase in mitochondrial membrane potential in C2C12 myotubes. Furthermore, a comprehensive examination of gene expression patterns through transcriptome-wide microarray analysis indicated that STEE altered gene expressions related to mitochondrial functions, fatty acid metabolism, inflammatory cytokines, mitogen-activated protein kinase (MAPK) signaling, and cAMP signaling in both C2C12 myotubes and HepG2 hepatocytes. Additionally, protein-protein interaction analysis identified the PGC-1α interactive-transcription factors-targeted regulatory network of the genes regulated by STEE, and the quantitative polymerase chain reaction results confirmed that STEE and its polyphenols upregulated the transcript levels of PGC-1α in both C2C12 and HepG2 cells. These findings collectively suggest the potential beneficial effects of STEE on muscle and liver tissues and offer novel insights into the potential nutraceutical applications of this material.

Recent Insights into the Biomarkers, Molecular Targets and Mechanisms of Non-Alcoholic Steatohepatitis-Driven Hepatocarcinogenesis

Non-alcoholic fatty liver disease (NAFLD) or metabolic dysfunction-associated steatotic liver disease (MASLD) and steatohepatitis (NASH) are chronic hepatic conditions leading to hepatocellular carcinoma (HCC) development. According to the recent "multiple-parallel-hits hypothesis", NASH could be caused by abnormal metabolism, accumulation of lipids, mitochondrial dysfunction, and oxidative and endoplasmic reticulum stresses and is found in obese and non-obese patients. Recent translational research studies have discovered new proteins and signaling pathways that are involved not only in the development of NAFLD but also in its progression to NASH, cirrhosis, and HCC. Nevertheless, the mechanisms of HCC developing from precancerous lesions have not yet been fully elucidated. Now, it is of particular importance to start research focusing on the discovery of novel molecular pathways that mediate alterations in glucose and lipid metabolism, which leads to the development of liver steatosis. The role of mTOR signaling in NASH progression to HCC has recently attracted attention. The goals of this review are (1) to highlight recent research on novel genetic and protein contributions to NAFLD/NASH; (2) to investigate how recent scientific findings might outline the process that causes NASH-associated HCC; and (3) to explore the reliable biomarkers/targets of NAFLD/NASH-associated hepatocarcinogenesis.

Targeted MicroRNA Profiling Reveals That Exendin-4 Modulates the Expression of Several MicroRNAs to Reduce Steatosis in HepG2 Cells

Excess hepatic lipid accumulation is the hallmark of non-alcoholic fatty liver disease (NAFLD), for which no medication is currently approved. However, glucagon-like peptide-1 receptor agonists (GLP-1RAs), already approved for treating type 2 diabetes, have lately emerged as possible treatments. Herein we aim to investigate how the GLP-1RA exendin-4 (Ex-4) affects the microRNA (miRNAs) expression profile using an in vitro model of steatosis. Total RNA, including miRNAs, was isolated from control, steatotic, and Ex-4-treated steatotic cells and used for probing a panel of 799 highly curated miRNAs using NanoString technology. Enrichment pathway analysis was used to find the signaling pathways and cellular functions associated with the differentially expressed miRNAs. Our data shows that Ex-4 reversed the expression of a set of miRNAs. Functional enrichment analysis highlighted many relevant signaling pathways and cellular functions enriched in the differentially expressed miRNAs, including hepatic fibrosis, insulin receptor, PPAR, Wnt/β-Catenin, VEGF, and mTOR receptor signaling pathways, fibrosis of the liver, cirrhosis of the liver, proliferation of hepatic stellate cells, diabetes mellitus, glucose metabolism disorder and proliferation of liver cells. Our findings suggest that miRNAs may play essential roles in the processes driving steatosis reduction in response to GLP-1R agonists, which warrants further functional investigation.

Atorvastatin and Flaxseed Effects on Biochemical Indices and Hepatic Fat of NAFLD Model in Rats

Background

Non-alcoholic fatty liver disease (NAFLD) is one of the most common forms of chronic liver disease that affects about 25% of the general population. No definitive treatment for NAFLD has been identified yet. The aim was to determine the effect of atorvastatin (ATO) and flaxseed on related indicators of NAFLD-induced fat/fructose-enriched diet (FFD).

Materials and Methods

Forty male Wistar rats were divided into five groups. NAFLD groups received FFD and carbon tetrachloride (CCl4) to induce NAFLD. After intervention with ATO (10 mg/kg/day) and/or flaxseed (7.5 g/kg/day), liver enzymes and lipid profiles in serum were determined at eight week of interventions.

Results

Triglycerides (TG) and cholesterol (CHO) in FFD + ATO, FFD + flaxseed, and FFD + ATO + flaxseed had a significant decrease and low-density lipoprotein (LDL) level and LDL/high-density lipoprotein (HDL) ratio showed a significant increase in the FFD + flaxseed compared to the FFD. The levels of aspartate transaminase (AST), alanine transaminase (ALT), and gamma-glutamyltransferase (GGT) were significantly reduced in the FFD + ATO, FFD + flaxseed, and the FFD + ATO + flaxseed. In addition, Alkaline phosphatase (ALP) levels were significantly different between normal and FFD. Fasting blood sugar (FBS) levels were significantly different in the FFD + flaxseed and the FFD + ATO + flaxseed compared to the FFD.

Conclusion

ATO therapy along with flaxseed controls NAFLD-related indices and FBS. Therefore, it can be stated with caution that ATO and flaxseed can be used to improve lipid profile and reduce the complications of NAFLD.

Metabolomics and Lipidomics Screening Reveal Reprogrammed Signaling Pathways toward Cancer Development in Non-Alcoholic Steatohepatitis

With the rising incidence of hepatocellular carcinoma (HCC) from non-alcoholic steatohepatitis (NASH), identifying new metabolic readouts that function in metabolic pathway perpetuation is still a demand. The study aimed to compare the metabolic signature between NASH and NASH-HCC patients to explore novel reprogrammed metabolic pathways that might modulate cancer progression in NASH patients. NASH and NASH-HCC patients were recruited and screened for metabolomics, and isotope-labeled lipidomics were targeted and profiled using the EXION-LCTM system equipped with a Triple-TOFTM 5600+ system. Results demonstrated significantly (p ≤ 0.05) higher levels of triacylglycerol, AFP, AST, and cancer antigen 19-9 in NASH-HCC than in NASH patients, while prothrombin time, platelet count, and total leukocyte count were decreased significantly (p ≤ 0.05). Serum metabolic profiling showed a panel of twenty metabolites with 10% FDR and p ≤ 0.05 in both targeted and non-targeted analysis that could segregate NASH-HCC from NASH patients. Pathway analysis revealed that the metabolites are implicated in the down-regulation of necroptosis, amino acid metabolism, and regulation of lipid metabolism by PPAR-α, biogenic amine synthesis, fatty acid metabolism, and the mTOR signaling pathway. Cholesterol metabolism, DNA repair, methylation pathway, bile acid, and salts metabolism were significantly upregulated in NASH-HCC compared to the NASH group. Metabolite-protein interactions network analysis clarified a set of well-known protein encoding genes that play crucial roles in cancer, including PEMT, IL4I1, BAAT, TAT, CDKAL1, NNMT, PNP, NOS1, and AHCYL. Taken together, reliable metabolite fingerprints are presented and illustrated in a detailed map for the most predominant reprogrammed metabolic pathways that target HCC development from NASH.

The role of drug-metabolizing enzymes in synthetic lethality of cancer

Drug-metabolizing enzymes (DMEs) have shown increasing importance in anticancer therapy. It is not only due to their effect on activation or deactivation of anticancer drugs, but also because of their extensive connections with pathological and biochemistry changes during tumorigenesis. Meanwhile, it has become more accessible to discovery anticancer drugs that selectively targeted cancer cells with the development of synthetic lethal screen technology. Synthetic lethal strategy makes use of unique genetic markers that different cancer cells from normal tissues to discovery anticancer agents. Dysregulation of DMEs has been found in various cancers, making them promising candidates for synthetic lethal strategy. In this review, we will systematically discuss about the role of DMEs in tumor progression, the application of synthetic lethality strategy in drug discovery, and a link between DMEs and synthetic lethal of cancer.

Lipid accumulation and oxidative stress in the crop tissues of male and female pigeons during incubation and chick-rearing periods

The current study aimed to evaluate the changes in lipid accumulation and oxidative status in pigeon crops during different breeding stages. Forty-two pairs of adult pigeons were randomly assigned to 7 groups. Lipid droplet accumulation in pigeon crops was visualized by using oil red O staining from d 17 of incubation (I17) to d 7 of chick rearing (R7). Transmission electron microscopy analysis showed swollen mitochondria with disintegration of cristae and typical characteristics of endoplasmic reticulum stress in crop tissues at R1 compared with those at I4. During the peak of pigeon milk formation, the concentrations of reactive oxygen species, and oxidative damage markers (advanced oxidation protein products, 8-hydroxy-2 deoxyguanosine, and malondialdehyde) and the enzyme activities of total superoxide dismutase and glutathione peroxidase were all elevated significantly (P < 0.05). The protein concentration of B-cell lymphoma-2 associated X in crop tissues was significantly higher at R1, while the level of B-cell lymphoma-2 protein in males was the highest at I4 (P < 0.05). The ratio of B-cell lymphoma-2 associated X protein (Bax)/B-cell lymphoma-2 (Bcl-2) in both male and female crops peaked at R1 (P < 0.05). Gene expression of the key enzymes involved in mitochondrial and peroxisomal fatty acid β-oxidation was investigated in crops. In males, the gene expression of carnitine palmitoyltransferase 1a peaked at R15, and that of carnitine palmitoyltransferase 2 increased significantly from R1 to R15 (P < 0.05). The mRNA abundance of long chain 3-hydroxyacyl-CoA dehydrogenase increased to the maximum value at R1 and I17 in males and females, respectively. From I17 to R7, the mRNA levels of acyl-CoA oxidase 1 and acyl-CoA oxidase 2 were decreased in pigeon crops (P < 0.05). Conclusively, lipid droplet accumulation was found in male and female pigeon crops from the end of incubation to the early stage of chick rearing. Although antioxidant defence and mitochondrial fatty acid β-oxidation were both mobilized, oxidative stress in crop tissues still occurred during the peak of milk formation.

Capparis spinosa improves non-alcoholic steatohepatitis through down-regulating SREBP-1c and a PPARα-independent pathway in high-fat diet-fed rats

Objective

Non-alcoholic steatohepatitis (NASH) has become a global medical problem. Currently, there is no approved pharmacologic treatment for this condition. Previous studies have suggested that in the pathogenesis of this disease, regulatory pathways associated with de novo lipogenesis and β-oxidation pathways genes are misregulated. Capparis spinosa (CS) belongs to the family of Capparidaceae and is a traditional plant used to treat various diseases, particularly dyslipidemia. The compounds and extracts of this plant in In vivo and in vitro studies resulted in a reduction in lipid profiles and glucose. However, the mechanism of these effects remains unknown. This study aimed to evaluate the effects of (CS) fruit extract on NASH compared to fenofibrate and explored the related molecular mechanism.

Results

In the rats (n = 40) model of NASH, biochemical and histopathological examinations showed that liver steatosis, inflammation, and hepatic fibrosis were markedly attenuated in response to CS and fenofibrate interventions. At the molecular level, CS treatment down-regulated sterol regulatory element-binding protein-1c (SREBP-1c) (p < 0.001), acetyl-CoA carboxylase (ACC) (p < 0.001), and up-regulated Carnitine palmitoyltransferase I (CPT1) expression (p < 0.001). In conclusion, CS has favorable therapeutic effects for NASH, which was associated with ameliorating steatosis and fibrosis via regulation of the DNL and β-oxidation pathway genes.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13104-022-06205-x.

Effects of an Herbal Source of Choline on Diet Digestibility and Palatability, Blood Lipid Profile, Liver Morphology, and Cardiac Function in Dogs

We aimed to evaluate the effects of an herbal source of choline on the coefficients of total tract apparent digestibility (CTTAD), diet palatability, fecal characteristics, blood variables, liver morphology, and cardiac function of dogs. Sixteen adult dogs were randomly assigned to two groups (n = 8) which were fed two different diets for 45 days: control, containing 0.28% choline chloride 60, and test, containing 0.14% of an herbal source of choline. Feces were collected between days 39 and 44 to determine nutrient CTTAD and fecal characteristics. On days 0 and 45, blood samples were collected and the liver morphology was evaluated. Cardiac function, in turn, was evaluated only on day 45, and the palatability test was performed on two consecutive days (n = 32). There were no changes in nutrient CTTAD, diet palatability, or fecal characteristics of dogs fed the test diet (p > 0.05). However, on day 45, dogs fed the test diet showed lower (p < 0.05) serum total cholesterol, triglycerides, alkaline phosphatase, and alanine aminotransferase when compared to the control group. We concluded that the herbal source of choline can be a possible substitute for choline chloride in dog nutrition.

Phthalate Exposures and Placental Health in Animal Models and Humans: A Systematic Review

Phthalates are ubiquitous compounds known to leach from the plastic products that contain them. Due to their endocrine-disrupting properties, a wide range of studies have elucidated their effects on reproduction, metabolism, neurodevelopment, and growth. Additionally, their impacts during pregnancy and on the developing fetus have been extensively studied. Most recently, there has been interest in the impacts of phthalates on the placenta, a transient major endocrine organ critical to maintenance of the uterine environment and fetal development. Phthalate-induced changes in placental structure and function may have significant impacts on the course of pregnancy and ultimately, child health. Prior reviews have described the literature on phthalates and placental health; however to date, there has been no comprehensive, systematic review on this topic. Here, we review 35 papers (24 human and 11 animal studies) and summarize phthalate exposures in relation to an extensive set of placental measures. Phthalate-related alterations were reported for placental morphology, hormone production, vascularization, histopathology, and gene/protein expression. The most consistent changes were observed in vascular and morphologic endpoints, including cell composition. These changes have implications for pregnancy complications such as preterm birth and intrauterine growth restriction as well as potential ramifications for children's health. This comprehensive review of the literature, including common sources of bias, will inform the future work in this rapidly expanding field.

Maternal dietary methionine restriction alters the expression of energy metabolism genes in the duckling liver

Background

In mammals, the nutritional status experienced during embryonic development shapes key metabolic pathways and influences the health and phenotype of the future individual, a phenomenon known as nutritional programming. In farmed birds as well, the quantity and quality of feed offered to the dam can impact the phenotype of the offspring. We have previously reported that a 38% reduction in the intake of the methyl donor methionine in the diet of 30 female ducks during the growing and laying periods - from 10 to 51 weeks of age - reduced the body weight of their 180 mule ducklings compared to that of 190 ducklings from 30 control females. The maternal dietary methionine restriction also altered the hepatic energy metabolism studied in 30 of their ducklings. Thus, their plasma glucose and triglyceride concentrations were higher while their plasma free fatty acid level was lower than those measured in the plasma of 30 ducklings from the control group. The objective of this new study was to better understand how maternal dietary methionine restriction affected the livers of their newly hatched male and female ducklings by investigating the hepatic expression levels of 100 genes primarily targeting energy metabolism, amino acid transport, oxidative stress, apoptotic activity and susceptibility to liver injury.

Results

Sixteen of the genes studied were differentially expressed between the ducklings from the two groups. Maternal dietary methionine restriction affected the mRNA levels of genes involved in different pathways related to energy metabolism such as glycolysis, lipogenesis or electron transport. Moreover, the mRNA levels of the nuclear receptors PPARGC1B, PPARG and RXRA were also affected.

Conclusions

Our results show that the 38% reduction in methionine intake in the diet of female ducks during the growing and egg-laying periods impacted the liver transcriptome of their offspring, which may explain the previously observed differences in their liver energy metabolism. These changes in mRNA levels, together with the observed phenotypic data, suggest an early modulation in the establishment of metabolic pathways.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-022-08634-1.

Influence of a Polyherbal Choline Source in Dogs: Body Weight Changes, Blood Metabolites, and Gene Expression

Choline chloride is used to provide choline in dog foods; however, in other domestic species, it has been replaced with a polyherbal containing phosphatidylcholine. A polyherbal containing Achyrantes aspera, Trachyspermum ammi, Citrullus colocynthis, Andrographis paniculata, and Azadirachta indica was evaluated in adult dogs through body weight changes, subcutaneous fat thickness, blood metabolites, and gene expression. Forty dogs (4.6 ± 1.6 years old) who were individually housed in concrete kennels were randomly assigned to the following treatments: unsupplemented diet (377 mg choline/kg), choline chloride (3850 mg/kg equivalent to 2000 mg choline/kg diet), and polyherbal (200, 400, and 800 mg/kg) for 60 days. Blood samples were collected on day 59 for biochemistry, biometry, and gene expression analysis through microarray assays. Intake, final body weight, and weight changes were similar for the two choline sources. Feed intake variation among dogs (p = 0.01) and dorsal fat (p = 0.03) showed a quadratic response to herbal choline. Dogs that received the polyherbal diet had reduced blood cholesterol levels (Quadratic, p = 0.02). The gene ontology analysis indicated that 15 biological processes were modified (p ≤ 0.05) with implications for preventing cardiovascular and metabolic diseases, cancer prevention, inflammatory and immune response, and behavior and cognitive process. According to these results that were observed in a 60 day trial, the polyherbal form could replace choline chloride in dog diets at a concentration of 400 mg/kg.

An integrated RNA sequencing and network pharmacology approach reveals the molecular mechanism of dapagliflozin in the treatment of diabetic nephropathy

Dapagliflozin, an inhibitor of sodium-glucose cotransporter 2 (SGLT2), is a new type of oral hypoglycemic drugs which can promote glucose excretion in the kidney. Studies have shown that dapagliflozin has renoprotective effect in the treatment of type 2 diabetes. However, the underlying mechanism remains unclear. Here, we combined integrated RNA sequencing and network pharmacology approach to investigate the molecular mechanism of dapagliflozin for diabetic nephropathy (DN). Dapagliflozin significantly relieved glucose intolerance, urinary albumin/creatinine ratio (UACR) and renal pathological injuries of db/db mice. The LncRNA and mRNA expression in kidney tissues from control group (CR), db/db group (DN) and dapagliflozin group (DG) were assessed by RNA sequencing. We identified 7 LncRNAs and 64 mRNAs common differentially expressed in CR vs DN and DN vs DG, which were used to construct co-expression network to reveal significantly correlated expression patterns in DN. In addition, network pharmacology was used to predict the therapeutic targets of dapagliflozin and we constructed component-target-pathway network according to the results of RNA sequencing and network pharmacology. We found that SMAD9, PPARG, CD36, CYP4A12A, CYP4A12B, CASP3, H2-DMB2, MAPK1, MAPK3, C3 and IL-10 might be the pivotal targets of dapagliflozin for treating DN and these genes were mainly enriched in pathways including TGF-β signaling pathway, PPAR signaling pathway, Chemokine signaling pathway, etc. Our results have important implication and provide novel insights into the protective mechanism of dapagliflozin for treating DN.

The CYP/20-HETE/GPR75 axis in hypertension

20-Hydroxyeicosatetraenoic acid (20-HETE) is a bioactive lipid generated from the ω-hydroxylation of arachidonic acid (AA) by enzymes of the cytochrome P450 (CYP) family, primarily the CYP4A and CYP4F subfamilies. 20-HETE is most notably identified as a modulator of vascular tone, regulator of renal function, and a contributor to the onset and development of hypertension and cardiovascular disease. 20-HETE-mediated signaling promotes hypertension by sensitizing the vasculature to constrictor stimuli, inducing endothelial dysfunction, and potentiating vascular inflammation. These bioactions are driven by the activation of the G-protein coupled receptor 75 (GPR75), a 20-HETE receptor (20HR). Given the capacity of 20-HETE signaling to drive pro-hypertensive mechanisms, the CYP/20-HETE/GPR75 axis has the potential to be a significant therapeutic target for the treatment of hypertension and cardiovascular diseases associated with increases in blood pressure. In this chapter, we review 20-HETE-mediated cellular mechanisms that promote hypertension, highlight important data in humans such as genetic variants in the CYP genes that potentiate 20-HETE production and describe recent findings in humans with 20HR/GPR75 mutations. Special emphasis is given to the 20HR and respective receptor blockers that have the potential to pave a path to translational and clinical studies for the treatment of 20-HETE-driven hypertension, and obesity/metabolic syndrome.

The transcriptome of early GGT/KRT19-positive hepatocellular carcinoma reveals a downregulated gene expression profile associated with fatty acid metabolism

Hepatocellular carcinoma expressing hepatobiliary progenitor markers, is considered of poor prognosis. By using a hepatocarcinogenesis model, laser capture microdissection, and RNA-Sequencing analysis, we identified an expression profile in GGT/KRT19-positive experimental tumors; 438 differentially expressed genes were found in early and late nodules along with increased collagen deposition. Dysregulated genes were involved in Fatty Acid Metabolism, RXR function, and Hepatic Stellate Cells Activation. Downregulation of Slc27a5, Acsl1, and Cyp2e1, demonstrated that Retinoid X Receptor α (RXRα) function is compromised in GGT/KRT19-positive nodules. Since RXRα controls NRF2 pathway activation, we determined the expression of NRF2 targeted genes; Akr1b8, Akr7a3, Gstp1, Abcc3, Ptgr1, and Txnrd1 were upregulated, indicating NRF2 pathway activation. A comparative analysis in human HCC showed that SLC27A5, ACSL1, CYP2E1, and RXRα gene expression is mutually exclusive with KRT19 gene expression. Our results indicate that the downregulation of Slc27a5, Acsl1, Rxrα, and Cyp2e1 genes is an early event within GGT/KRT19-positive HCC.

CYP4V2 fatty acid omega hydroxylase, a druggable target for the treatment of metabolic associated fatty liver disease (MAFLD)

Fatty acids are essential in maintaining cellular homeostasis by providing lipids for energy production, cell membrane integrity, protein modification, and the structural demands of proliferating cells. Fatty acids and their derivatives are critical bioactive signaling molecules that influence many cellular processes, including metabolism, cell survival, proliferation, migration, angiogenesis, and cell barrier function. The CYP4 Omega hydroxylase gene family hydroxylate various short, medium, long, and very-long-chain saturated, unsaturated and polyunsaturated fatty acids. Selective members of the CYP4 family metabolize vitamins and biochemicals with long alkyl side chains and bioactive prostaglandins, leukotrienes, and arachidonic acids. It is uncertain of the physiological role of different members of the CYP4 omega hydroxylase gene family in the metabolic control of physiological and pathological processes in the liver. CYP4V2 is a unique member of the CYP4 family. CYP4V2 inactivation in retinal pigment epithelial cells leads to cholesterol accumulation and Bietti's Crystalline Dystrophy (BCD) pathogenesis. This commentary provides information on the role CYP4V2 has in metabolic syndrome and nonalcoholic fatty liver disease progression. This is accomplished by identifying its role in BCD, its control of cholesterol synthesis and lipid droplet formation in C. elegans, and the putative function in cardiovascular disease and gastrointestinal/hepatic pathologies.

Ethanol Extract of Liriope platyphylla Root Attenuates Non-Alcoholic Fatty Liver Disease in High-Fat Diet-Induced Obese Mice via Regulation of Lipogenesis and Lipid Uptake

Non-alcoholic fatty liver disease (NAFLD) is a common metabolic disorder that causes excess lipid accumulation in the liver and is the leading cause of end-stage liver disease. Liriope platyphylla is a medicinal herb that has long been used to treat cough, obesity, and diabetes. However, the effect of Liriope platyphylla on NAFLD has not been studied. The aim of this study was to investigate the effect of Liriope platyphylla root ethanolic extract (LPE) on hepatic lipid accumulation in high-fat diet (HFD)-induced obese mice. Six-week-old C57BL/6 male mice were fed a HFD for 8 weeks and then treated with LPE (100 or 250 mg/kg/day) by oral gavage for another 8 weeks. Body weight gain and liver weight were significantly lower in the 250 mg/kg LPE-treated HFD group than in the vehicle-treated HFD group. Histological analysis of liver sections demonstrated that LPE treatment reduced lipid accumulation compared to the vehicle treatment. The serum total cholesterol, AST, and ALT levels significantly decreased in the LPE-treated HFD group compared to those in the vehicle-treated HFD group. The LPE significantly decreases the protein expression levels of SREBP1, ACC, p-ACC, FAS, and SCD1, which are involved in lipogenesis, and PPARγ, CD36/FAT, and FATP5, which are involved in fatty acid uptake, both in vivo and in vitro. Thus, LPE may attenuate HFD-induced NAFLD by decreasing lipid accumulation by inhibiting lipogenesis and fatty acid uptake.

Effects of Short- and Long-Term Soy Protein Feeding on Hepatic Cytochrome P450 Expression in Obese Nonalcoholic Fatty Liver Disease Rat Model

Obesity can lead to chronic health complications such as nonalcoholic fatty liver disease (NAFLD). NAFLD is characterized by lipid aggregation in the hepatocytes and inflammation of the liver tissue as a consequence that can contribute to the development of cirrhosis and hepatocellular carcinoma (HCC). Previously, we reported that feeding obese Zucker rats with soy protein isolate (SPI) can reduce liver steatosis when compared with a casein (CAS) diet as a control. However, the effects of SPI on cytochrome P450 (CYP) in an obese rat model are less known. In addition, there is a lack of information concerning the consumption of soy protein in adolescents and its effect in reducing the early onset of NAFLD in this group. Our main goal was to understand if the SPI diet had any impact on the hepatic CYP gene expression when compared with the CAS diet. For this purpose, we used the transcriptomic data obtained in a previous study in which liver samples were collected from obese rats after short-term (eight-week) and long-term (16-week) feeding of SPI (n = 8 per group). To analyze this RNAseq data, we used Ingenuity Pathway Analysis (IPA) software. Comparing short- vs long-term feeding revealed an increase in the number of downregulated CYP genes from three at 8 weeks of SPI diet to five at 16 weeks of the same diet (P ≤ 0.05). On the other hand, upregulated CYP gene numbers showed a small increase in the long-term SPI diet compared to the short-term SPI diet, from 14 genes at 8 weeks to 17 genes at 16 weeks (P ≤ 0.05). The observed changes may have an important role in the attenuation of liver steatosis.

SMN Depleted Mice Offer a Robust and Rapid Onset Model of Nonalcoholic Fatty Liver Disease

BACKGROUND & AIMS

Nonalcoholic fatty liver disease (NAFLD) is considered a health epidemic with potential devastating effects on the patients and the healthcare systems. Current preclinical models of NAFLD are invariably imperfect and generally take a long time to develop. A mouse model of survival motor neuron (SMN) depletion (Smn^2B/- mice) was recently shown to develop significant hepatic steatosis in less than 2 weeks from birth. The rapid onset of fatty liver in Smn^2B/- mice provides an opportunity to identify molecular markers of NAFLD. Here, we investigated whether Smn^2B/- mice display typical features of NAFLD/nonalcoholic steatohepatitis (NASH).

METHODS

Biochemical, histologic, electron microscopy, proteomic, and high-resolution respirometry were used.

RESULTS

The Smn^2B/- mice develop microvesicular steatohepatitis within 2 weeks, a feature prevented by AAV9-SMN gene therapy. Although fibrosis is not overtly apparent in histologic sections of the liver, there is molecular evidence of fibrogenesis and presence of stellate cell activation. The consequent liver damage arises from mitochondrial reactive oxygen species production and results in hepatic dysfunction in protein output, complement, coagulation, iron homeostasis, and insulin-like growth factor-1 metabolism. The NAFLD phenotype is likely due to non-esterified fatty acid overload from peripheral lipolysis subsequent to hyperglucagonemia compounded by reduced muscle use and insulin resistance. Despite the low hepatic mitochondrial content, isolated mitochondria show enhanced β-oxidation, likely as a compensatory response, resulting in the production of reactive oxygen species. In contrast to typical NAFLD/NASH, the Smn^2B/- mice lose weight because of their associated neurological condition (spinal muscular atrophy) and develop hypoglycemia.

CONCLUSIONS

The Smn^2B/- mice represent a good model of microvesicular steatohepatitis. Like other models, it is not representative of the complete NAFLD/NASH spectrum. Nevertheless, it offers a reliable, low-cost, early-onset model that is not dependent on diet to identify molecular players in NAFLD pathogenesis and can serve as one of the very few models of microvesicular steatohepatitis for both adult and pediatric populations.

An Integrated Analysis of miRNA and Gene Expression Changes in Response to an Obesogenic Diet to Explore the Impact of Transgenerational Supplementation with Omega 3 Fatty Acids

Insulin resistance decreases the ability of insulin to inhibit hepatic gluconeogenesis, a key step in the development of metabolic syndrome. Metabolic alterations, fat accumulation, and fibrosis in the liver are closely related and contribute to the progression of comorbidities, such as hypertension, type 2 diabetes, or cancer. Omega 3 (n-3) polyunsaturated fatty acids, such as eicosapentaenoic acid (EPA), were identified as potent positive regulators of insulin sensitivity in vitro and in animal models. In the current study, we explored the effects of a transgenerational supplementation with EPA in mice exposed to an obesogenic diet on the regulation of microRNAs (miRNAs) and gene expression in the liver using high-throughput techniques. We implemented a comprehensive molecular systems biology approach, combining statistical tools, such as MicroRNA Master Regulator Analysis pipeline and Boolean modeling to integrate these biochemical processes. We demonstrated that EPA mediated molecular adaptations, leading to the inhibition of miR-34a-5p, a negative regulator of Irs2 as a master regulatory event leading to the inhibition of gluconeogenesis by insulin during the fasting-feeding transition. Omics data integration provided greater biological insight and a better understanding of the relationships between biological variables. Such an approach may be useful for deriving innovative data-driven hypotheses and for the discovery of molecular-biochemical mechanistic links.

Triclosan leads to dysregulation of the metabolic regulator FGF21 exacerbating high fat diet-induced nonalcoholic fatty liver disease

Triclosan (TCS), employed as an antiseptic and disinfectant, comes into direct contact with humans through a plethora of consumer products and its rising environmental release. We have demonstrated that TCS promotes liver tumorigenesis in mice, yet the biological and molecular mechanisms by which TCS exerts its toxicity, especially in early stages of liver disease, are largely unexplored. When mice were fed a high-fat diet (HFD), we found that fatty liver and dyslipidemia are prominent early signs of liver abnormality induced by TCS. The presumably protective HFD-induced hepatic expression of the metabolic regulator fibroblast growth factor 21 (FGF21) was blunted by TCS. TCS-altered Fgf21 expression aligned with aberrant expression of genes encoding metabolic enzymes manifested as profound systemic metabolic changes that disturb homeostasis of amino acids, fatty acids, and glucose. Using a type 1 diabetic animal model, TCS potentiates and accelerates the development of steatohepatitis and fibrosis, accompanied by increased levels of hepatic lipid droplets and oxidative stress. Analysis of fecal samples revealed that HFD-fed mice exhibited a reduction in fecal species richness, and that TCS further diminished microbial diversity and shifted the bacterial community toward lower Bacteriodetes and higher Firmicutes, resembling changes in microbiota composition in nonalcoholic steatohepatitis (NASH) patients. Using reverse-genetic approaches, we demonstrate that, along with HFD, TCS induces hepatic steatosis and steatohepatitis jointly regulated by the transcription factor ATF4 and the nuclear receptor PPARα, which participate in the transcriptional regulation of the Fgf21 gene. This study provides evidence linking nutritional imbalance and exposure to TCS with the progression of NASH.

Vitamin E catabolism in women, as modulated by food and by fat, studied using 2 deuterium-labeled α-tocopherols in a 3-phase, nonrandomized crossover study

BACKGROUND

Human vitamin E (α-tocopherol) catabolism is a mechanism for regulating whole-body α-tocopherol.

OBJECTIVES

To determine the roles of the intestine and liver on α-tocopherol catabolism as affected by fat or fasting, 2 deuterium-labeled (intravenous d6- and oral d3-) forms of α-tocopherol were used.

METHODS

Healthy women received intravenous d6-α-tocopherol and consumed d3-α-tocopherol with a 600-kcal defined liquid meal (DLM; 40% or 0% fat, n = 10) followed by controlled meals; or the 0% fat DLM (n = 7) followed by a 12-h fast (0% fat-fast), then controlled meals ≤72 h. The order of the 3-phase crossover design was not randomized and there was no blinding. Samples were analyzed by LC/MS to determine the α-tocopherol catabolites and α-carboxyethyl hydroxychromanol (α-CEHC) in urine, feces, and plasma that were catabolized from administered oral d3- and intravenous d6-α-tocopherols.

RESULTS

Urinary and plasma d3- and d6-α-CEHC concentrations varied differently with the interventions. Mean ± SEM cumulative urinary d6-α-CEHC derived from the intravenous dose excreted over 72 h during the 40% fat (2.50 ± 0.37 μmol/g creatinine) and 0% fat (2.37 ± 0.37 μmol/g creatinine) interventions were similar, but a ∼50% decrease was observed during the 0% fat-fast (1.05 ± 0.39 μmol/g creatinine) intervention (compared with 0% fat, P = 0.0005). Cumulative urinary d3-α-CEHC excretion was not significantly changed by any intervention. Total urinary and fecal excretion of catabolites accounted for <5% of each of the administered doses.

CONCLUSIONS

Differential catabolism of the intravenous d6-α-tocopherol and oral d3-α-tocopherol doses shows both liver and intestine have roles in α-tocopherol catabolism. During the 40% fat intervention, >90% of urinary d3-α-CEHC excretion was estimated to be liver-derived, whereas during fasting <50% was from the liver with the remainder from the intestine, suggesting that there was increased intestinal α-tocopherol catabolism while d3-α-tocopherol was retained in the intestine in the absence of adequate fat/food for α-tocopherol absorption.This trial was registered at clinicaltrials.gov as NCT00862433.

Beyond Fish Oil Supplementation: The Effects of Alternative Plant Sources of Omega-3 Polyunsaturated Fatty Acids upon Lipid Indexes and Cardiometabolic Biomarkers-An Overview

Cardiovascular diseases remain a global challenge, and lipid-associated biomarkers can predict cardiovascular events. Extensive research on cardiovascular benefits of omega-3 polyunsaturated fatty acids (n3-PUFAs) is geared towards fish oil supplementation and fish-rich diets. Nevertheless, vegetarianism and veganism are becoming more popular across all segments of society, due to reasons as varied as personal, ethical and religious values, individual preferences and environment-related principles, amongst others. Due to the essentiality of PUFAs, plant sources of n3-PUFAs warrant further consideration. In this review, we have critically appraised the efficacy of plant-derived n3-PUFAs from foodstuffs and supplements upon lipid profile and selected cardiometabolic markers. Walnuts and flaxseed are the most common plant sources of n3-PUFAs, mainly alpha-linolenic acid (ALA), and feature the strongest scientific rationale for applicability into clinical practice. Furthermore, walnuts and flaxseed are sources of fibre, potassium, magnesium, and non-essential substances, including polyphenols and sterols, which in conjunction are known to ameliorate cardiovascular metabolism. ALA levels in rapeseed and soybean oils are only slight when compared to flaxseed oil. Spirulina and Chlorella, biomasses of cyanobacteria and green algae, are important sources of n3-PUFAs; however, their benefits upon cardiometabolic markers are plausibly driven by their antioxidant potential combined with their n3-PUFA content. In humans, ALA is not sufficiently bioconverted into eicosapentaenoic and docosahexaenoic acids. However, evidence suggests that plant sources of ALA are associated with favourable cardiometabolic status. ALA supplementation, or increased consumption of ALA-rich foodstuffs, combined with reduced omega-6 (n6) PUFAs intake, could improve the n3/n6 ratio and improve cardiometabolic and lipid profile.

MEHP/ethanol co-exposure favors the death of steatotic hepatocytes, possibly through CYP4A and ADH involvement

Liver steatosis has been associated with various etiological factors (obesity, alcohol, environmental contaminants). How those factors work together to induce steatosis progression is still scarcely evaluated. Here, we tested whether phthalates could potentiate death of steatotic hepatocytes when combined with ethanol. Pre-steatotic WIF-B9 hepatocytes were co-exposed to mono (2-ethylhexyl) (MEHP, 500 nM; main metabolite of di (2-ethylhexyl) phthalate or DEHP) and ethanol (5 mM) for 5 days. An increased apoptotic death was detected, involving a DNA damage response. Using 4-Methypyrazole to inhibit ethanol metabolism, and CH-223191 to antagonize the AhR receptor, we found that an AhR-dependent increase in alcohol dehydrogenase (ADH) activity was essential for cell death upon MEHP/ethanol co-exposure. Toxicity was also prevented by HET0016 to inhibit the cytochrome P450 4A (CYP4A). Using the antioxidant thiourea, a role for oxidative stress was uncovered, notably triggering DNA damage. Finally, co-exposing the in vivo steatosis model of high fat diet (HFD)-zebrafish larvae to DEHP (2.56 nM)/ethanol (43 mM), induced the pathological progression of liver steatosis alongside an increased Cyp4t8 (human CYP4A homolog) mRNA expression. Altogether, these results further emphasized the deleterious impact of co-exposures to ethanol/environmental pollutant towards steatosis pathological progression, and unraveled a key role for ADH and CYP4A in such effects.

Nervonic acid limits weight gain in a mouse model of diet-induced obesity

Lipid perturbations contribute to detrimental outcomes in obesity. We previously demonstrated that nervonic acid, a C24:1 ω-9 fatty acid, predominantly acylated to sphingolipids, including ceramides, are selectively reduced in a mouse model of obesity. It is currently unknown if deficiency of nervonic acid-sphingolipid metabolites contribute to complications of obesity. Mice were fed a standard diet, a high fat diet, or these diets supplemented isocalorically with nervonic acid. The primary objective was to determine if dietary nervonic acid content alters the metabolic phenotype in mice fed a high fat diet. Furthermore, we investigated if nervonic acid alters markers of impaired fatty acid oxidation in the liver. We observed that a nervonic acid-enriched isocaloric diet reduced weight gain and adiposity in mice fed a high fat diet. The nervonic acid enrichment led to increased C24:1-ceramides and improved several metabolic parameters including blood glucose levels, and insulin and glucose tolerance. Mechanistically, nervonic acid supplementation increased PPARα and PGC1α expression and improved the acylcarnitine profile in liver. These alterations indicate improved energy metabolism through increased β-oxidation of fatty acids. Taken together, increasing dietary nervonic acid improves metabolic parameters in mice fed a high fat diet. Strategies that prevent deficiency of, or restore, nervonic acid may represent an effective strategy to treat obesity and obesity-related complications.

Omega-3 Phospholipids from Krill Oil Enhance Intestinal Fatty Acid Oxidation More Effectively than Omega-3 Triacylglycerols in High-Fat Diet-Fed Obese Mice

Antisteatotic effects of omega-3 fatty acids (Omega-3) in obese rodents seem to vary depending on the lipid form of their administration. Whether these effects could reflect changes in intestinal metabolism is unknown. Here, we compare Omega-3-containing phospholipids (krill oil; ω3PL-H) and triacylglycerols (ω3TG) in terms of their effects on morphology, gene expression and fatty acid (FA) oxidation in the small intestine. Male C57BL/6N mice were fed for 8 weeks with a high-fat diet (HFD) alone or supplemented with 30 mg/g diet of ω3TG or ω3PL-H. Omega-3 index, reflecting the bioavailability of Omega-3, reached 12.5% and 7.5% in the ω3PL-H and ω3TG groups, respectively. Compared to HFD mice, ω3PL-H but not ω3TG animals had lower body weight gain (−40%), mesenteric adipose tissue (−43%), and hepatic lipid content (−64%). The highest number and expression level of regulated intestinal genes was observed in ω3PL-H mice. The expression of FA ω-oxidation genes was enhanced in both Omega-3-supplemented groups, but gene expression within the FA β-oxidation pathway and functional palmitate oxidation in the proximal ileum was significantly increased only in ω3PL-H mice. In conclusion, enhanced intestinal FA oxidation could contribute to the strong antisteatotic effects of Omega-3 when administered as phospholipids to dietary obese mice.

Mycobacterium tuberculosis Rv3034c regulates mTORC1 and PPAR-γ dependant pexophagy mechanism to control redox levels in macrophages

Mycobacterium tuberculosis survives inside the macrophages by employing several host immune evasion strategies. Here, we reported a novel mechanism in which M. tuberculosis acetyltransferase, encoded by Rv3034c, induces peroxisome homeostasis to regulate host oxidative stress levels to facilitate intracellular mycobacterial infection. Presence of M. tuberculosis Rv3034c induces the expression of peroxisome biogenesis and proliferation factors such as Pex3, Pex5, Pex19, Pex11b, Fis-1 and DLP-1; while depletion of Rv3034c decreased the expression of these molecules, thereby selective degradation of peroxisomes via pexophagy. Further studies revealed that M. tuberculosis Rv3034c inhibit induction of pexophagy mechanism by down-regulating the expression of pexophagy associated proteins (p-AMPKα, p-ULK-1, Atg5, Atg7, Beclin-1, LC3-II, TFEB and Keap-1) and adaptor molecules (NBR1 and p62). Inhibition was found to be dependent on the phosphorylation of mTORC1 and activation of peroxisome proliferator activated receptor-γ. In order to maintain intracellular homeostasis during oxidative stress, M. tuberculosis Rv3034c was found to induce degradation of dysfunctional and damaged peroxisomes through activation of Pex14 in infected macrophages. In conclusion, this is the first report which demonstrated that M. tuberculosis acetyltransferase regulate peroxisome homeostasis in response to intracellular redox levels to favour mycobacterial infection in macrophage.

Farnesoid X receptor activation induces the degradation of hepatotoxic 1-deoxysphingolipids in non-alcoholic fatty liver disease

BACKGROUND & AIMS

Patients with non-alcoholic fatty liver disease (NAFLD) exhibit higher levels of plasma 1-deoxysphingolipids than healthy individuals. The aim of this study was to investigate the role of farnesoid X receptor (FXR) in 1-deoxysphingolipid de novo synthesis and degradation.

METHODS

Mice were fed with a high-fat diet (HFD) to induce obesity and NAFLD, and then treated with the FXR ligand obeticholic acid (OCA). Histology and gene expression analysis were performed on liver tissue. Sphingolipid patterns from NAFLD patients and mouse models were assessed by liquid chromatography-mass spectrometry. The molecular mechanism underlying the effect of FXR activation on sphingolipid metabolism was studied in Huh7 cells and primary cultured hepatocytes, as well as in a 1-deoxysphinganine-treated mouse model.

RESULTS

1-deoxysphingolipids were increased in both NAFLD patients and mouse models. FXR activation by OCA protected the liver against oxidative stress, apoptosis, and reduced 1-deoxysphingolipid levels, both in a HFD-induced mouse model of obesity and in 1-deoxysphinganine-treated mice. In vitro, FXR activation lowered intracellular 1-deoxysphingolipid levels by inducing Cyp4f-mediated degradation, but not by inhibiting de novo synthesis, thereby protecting hepatocytes against doxSA-induced cytotoxicity, mitochondrial damage, and apoptosis. Overexpression of Cyp4f13 in cells was sufficient to ameliorate doxSA-induced cytotoxicity. Treatment with the Cyp4f pan-inhibitor HET0016 or FXR knock-down fully abolished the protective effect of OCA, indicating that OCA-mediated 1-deoxysphingolipid degradation is FXR and Cyp4f dependent.

CONCLUSIONS

Our study identifies FXR-Cyp4f as a novel regulatory pathway for 1-deoxysphingolipid metabolism. FXR activation represents a promising therapeutic strategy for patients with metabolic syndrome and NAFLD.

Metabolic Syndrome Is Reduced in C57BL/6J Mice Fed High-Fat Diets Supplemented with Oak Tannins

BACKGROUND

Wine aged in oak barrels will incorporate polyphenols inherent in the staves, suggesting that wine stored in these wooden containers will introduce oak compounds into the human body after consumption.

OBJECTIVE

The purpose of the present study is to test whether consumption of these oak compounds could favorably influence metabolism in mice fed an obesogenic diet.

METHODS

C57BL/6  male mice (n = 8) were fed diets for 10 wk as follows: low-fat (LF), high-fat (HF), and HF containing 0.17% of oak tannin (HF+OT). A second 10-wk study was completed; mice were provided LF, HF, and HF diets supplemented with 7.0% of concentrates made from oaked wine (HF+OWC) or unoaked wine (HF+UWC). Physiological parameters were measured during the feeding trial and serum markers and hepatic gene expression measured from samples obtained at necropsy.

RESULTS

Intake of HF+OT significantly reduced body-weight gain (18.4 ± 1.2 g in HF vs. 13.2 ± 1.4 g in HF+OT, P < 0.05). Serum resistin concentrations were lower in HF+OT mice compared with HF mice (301 ± 10.1 pg/mL in HF+OT vs. 374 ± 10.9 pg/mL in HF; P < 0.05). Hepatic lipid accumulation and expression of glutathione-S-transferase-m2 (Gstm2) and NAD(P)H:quinone oxidoreductase (Nqo1) mRNAs were significantly decreased in HF+OT compared with HF mice (P < 0.05). When compared with HF-fed mice, intake of both OWC and UWC decreased body-weight gain (P < 0.05), with no significant impact on food consumption. Fasting glucose concentrations, serum insulin, and hepatic lipid accumulation were reduced in HF+OWC-fed mice compared with HF+UWC-fed mice (P < 0.05). Furthermore, hepatic glutathione-S-transferase-a1 (Gsta1) mRNA levels were significantly reduced in OWC-supplemented (0.25 ± 0.08) compared with UWC-supplemented (1.71 ± 0.24) mice (P < 0.05).

CONCLUSIONS

In this mouse model of metabolic disease, intake of OTs and a concentrate made from an oaked wine had a potent impact on alleviating HF-induced metabolic syndrome. Thus, intake of OTs, provided passively in oaked wine or as a dietary supplement, may act as an agent to attenuate the markers of metabolic syndrome.

Low fat diets increase survival of a mouse model of spinal muscular atrophy

Spinal muscular atrophy (SMA) is a neuromuscular disorder leading to paralysis and death. Recent evidence shows increased susceptibility to dyslipidemia and liver steatosis in patients. Here, we provide evidence that low fat diets nearly double survival in Smn^2B/− mice, a model for SMA, independent of changes in SMN levels, liver steatosis, or enhanced hepatic functions. Liver damage and ketone levels were reduced, implying a lower reliance on fatty acid oxidation. This preclinical proof of concept study provides grounds for controlled clinical investigation of dietary needs and offers evidence to inform nutritional guidelines specific to SMA.

Molecular Functionality of Cytochrome P450 4 (CYP4) Genetic Polymorphisms and Their Clinical Implications

Enzymes in the cytochrome P450 4 (CYP4) family are involved in the metabolism of fatty acids, xenobiotics, therapeutic drugs, and signaling molecules, including eicosanoids, leukotrienes, and prostanoids. As CYP4 enzymes play a role in the maintenance of fatty acids and fatty-acid-derived bioactive molecules within a normal range, they have been implicated in various biological functions, including inflammation, skin barrier, eye function, cardiovascular health, and cancer. Numerous studies have indicated that genetic variants of CYP4 genes cause inter-individual variations in metabolism and disease susceptibility. Genetic variants of CYP4A11, 4F2 genes are associated with cardiovascular diseases. Mutations of CYP4B1, CYP4Z1, and other CYP4 genes that generate 20-HETE are a potential risk for cancer. CYP4V2 gene variants are associated with ocular disease, while those of CYP4F22 are linked to skin disease and CYP4F3B is associated with the inflammatory response. The present study comprehensively collected research to provide an updated view of the molecular functionality of CYP4 genes and their associations with human diseases. Functional analysis of CYP4 genes with clinical implications is necessary to understand inter-individual variations in disease susceptibility and for the development of alternative treatment strategies.

The fate of medium-chain fatty acids in very long-chain acyl‑CoA dehydrogenase deficiency (VLCADD): A matter of sex?

Medium-chain-triglycerides (MCT) are widely applied in the treatment of long-chain fatty acid oxidation disorders (lcFAOD). Long-term treatment with MCT led to a sexually dimorphic response in the mouse model of very-long-chain-acyl-CoA-dehydrogenase-deficiency (VLCAD^-/-) with the subsequent development of a metabolic syndrome in female mice. In order to evaluate the molecular mechanisms responsible for this sex specific response we performed a comprehensive metabolic phenotyping, SILAC-based quantitative proteomics and characterized the involved signaling pathways by western blot analysis and gene expression. WT and VLCAD^-/- mice showed strong sex-dependent differences in basal metabolism and expression of proteins involved in the distinct metabolic pathways, even more prominent after treatment with octanoate. The investigation of molecular mechanisms responsible for the sexual dimorphisms delineated the selective activation of the ERK/mTORc1 signaling pathway leading to an increased biosynthesis and elongation of fatty acids in VLCAD^-/- females. In contrast, octanoate induced the activation of ERK/PPARγ pathway and the subsequent upregulation of peroxisomal β‑oxidation in males. We here provide first evidence that sex has to be considered as important variable in disease phenotype. These findings may have implications on treatment strategies in the different sexes.

Combined Analysis of Metabolomes, Proteomes, and Transcriptomes of Hepatitis C Virus-Infected Cells and Liver to Identify Pathways Associated With Disease Development

BACKGROUND & AIMS

The mechanisms of hepatitis C virus (HCV) infection, liver disease progression, and hepatocarcinogenesis are only partially understood. We performed genomic, proteomic, and metabolomic analyses of HCV-infected cells and chimeric mice to learn more about these processes.

METHODS

Huh7.5.1dif (hepatocyte-like cells) were infected with culture-derived HCV and used in RNA sequencing, proteomic, metabolomic, and integrative genomic analyses. uPA/SCID (urokinase-type plasminogen activator/severe combined immunodeficiency) mice were injected with serum from HCV-infected patients; 8 weeks later, liver tissues were collected and analyzed by RNA sequencing and proteomics. Using differential expression, gene set enrichment analyses, and protein interaction mapping, we identified pathways that changed in response to HCV infection. We validated our findings in studies of liver tissues from 216 patients with HCV infection and early-stage cirrhosis and paired biopsy specimens from 99 patients with hepatocellular carcinoma, including 17 patients with histologic features of steatohepatitis. Cirrhotic liver tissues from patients with HCV infection were classified into 2 groups based on relative peroxisome function; outcomes assessed included Child-Pugh class, development of hepatocellular carcinoma, survival, and steatohepatitis. Hepatocellular carcinomas were classified according to steatohepatitis; the outcome was relative peroxisomal function.

RESULTS

We quantified 21,950 messenger RNAs (mRNAs) and 8297 proteins in HCV-infected cells. Upon HCV infection of hepatocyte-like cells and chimeric mice, we observed significant changes in levels of mRNAs and proteins involved in metabolism and hepatocarcinogenesis. HCV infection of hepatocyte-like cells significantly increased levels of the mRNAs, but not proteins, that regulate the innate immune response; we believe this was due to the inhibition of translation in these cells. HCV infection of hepatocyte-like cells increased glucose consumption and metabolism and the STAT3 signaling pathway and reduced peroxisome function. Peroxisomes mediate β-oxidation of very long-chain fatty acids; we found intracellular accumulation of very long-chain fatty acids in HCV-infected cells, which is also observed in patients with fatty liver disease. Cells in livers from HCV-infected mice had significant reductions in levels of the mRNAs and proteins associated with peroxisome function, indicating perturbation of peroxisomes. We found that defects in peroxisome function were associated with outcomes and features of HCV-associated cirrhosis, fatty liver disease, and hepatocellular carcinoma in patients.

CONCLUSIONS

We performed combined transcriptome, proteome, and metabolome analyses of liver tissues from HCV-infected hepatocyte-like cells and HCV-infected mice. We found that HCV infection increases glucose metabolism and the STAT3 signaling pathway and thereby reduces peroxisome function; alterations in the expression levels of peroxisome genes were associated with outcomes of patients with liver diseases. These findings provide insights into liver disease pathogenesis and might be used to identify new therapeutic targets.

Molecular modelling, synthesis, and biological evaluations of a 3,5-disubstituted isoxazole fatty acid analogue as a PPARα-selective agonist

The peroxisome proliferator activated receptors (PPARs) are important drug targets in treatment of metabolic and inflammatory disorders. Fibrates, acting as PPARα agonists, have been widely used lipid-lowering agents for decades. However, the currently available PPARα targeting agents show low subtype-specificity and consequently a search for more potent agonists have emerged. In this study, previously isolated oxohexadecenoic acids from the marine algae Chaetoceros karianus were used to design a PPARα-specific analogue. Herein we report the design, synthesis, molecular modelling studies and biological evaluations of the novel 3,5-disubstituted isoxazole analogue 6-(5-heptyl-1,2-oxazol-3-yl)hexanoic acid (1), named ADAM. ADAM shows a clear receptor preference and significant dose-dependent activation of PPARα (EC₅₀ = 47 µM) through its ligand-binding domain (LBD). Moreover, ADAM induces expression of important PPARα target genes, such as CPT1A, in the Huh7 cell line and primary mouse hepatocytes. In addition, ADAM exhibits a moderate ability to regulate PPARγ target genes and drive adipogenesis. Molecular modelling studies indicated that ADAM docks its carboxyl group into opposite ends of the PPARα and -γ LBD. ADAM interacts with the receptor-activating polar network of amino acids (Tyr501, His447 and Ser317) in PPARα, but not in PPARγ LBD. This may explain the lack of PPARγ agonism, and argues for a PPARα-dependent adipogenic function. Such compounds are of interest towards developing new lipid-lowering remedies.

Dietary Aroclor 1254-Induced Toxicity on Antioxidant Capacity, Immunity and Energy Metabolism in Chinese Mitten Crab Eriocheir sinensis: Amelioration by Vitamin A

Effects of dietary Polychlorinated biphenyl (PCB) exposure and dietary vitamin A supplementation on Chinese mitten crab Eriocheir sinensis were studied with the aim to explain dietary PCB toxicity and toxic alleviation by vitamin A intake in crab. Four diets were used including three experimental diets containing 0, 80000 or 240000 IU/kg vitamin A with each experimental diet containing 10 mg PCB/kg diet, and a control diet (without vitamin A and PCB supplementation) in 56 days feeding trial. Crabs fed the PCB-only diet had significantly lower weight gain than those fed the control diet. No significant difference was observed in crab survival among all groups. Crabs fed the PCB-only diet had a significantly higher malondialdehyde content and antioxidase superoxide dismutase activity in the serum and hepatopancreas, and higher erythromycin N-demethylase and glutathione S-transferase activities in the hepatopancreas than those fed the control diet. However, supplementation of dietary vitamin A decreased the levels of all these parameters. The hepatopancreatic cytochrome P450 2 and 4 (CYP2, CYP4), fatty acid binding proteins 3 and 10 (FABP3, FABP10) and intracellular lipolytic enzyme (IL) Messenger Ribonucleic Acid (mRNA) levels in the PCB-only group were significantly higher than those in the control group, and dietary 240000 IU/kg vitamin A supplementation decreased hepatopancreatic CYP4, FABP3, FABP10 and IL enzyme mRNA level. The crabs fed 80000 IU/kg vitamin A supplementation diet had the highest level of retinoid X receptor mRNA in the hepatopancreas. The structure of the hepatopancreas was damaged and the deposit of lipid droplets decreased with dietary PCB exposure. Both levels of vitamin A supplementation alleviated the damage and increased lipid droplets in the hepatopancreas. Dietary PCB exposure significantly reduced total hemocyte count (THC), and phenoloxidase, acid phosphatase activities in the serum. Post-challenge survival of crab in the experimental PCB-only diet group was low compared with that in the control. Supplementation of 240000 IU/kg vitamin A significantly increased the THC and phenoloxidase activity in the serum and post-challenge survival compared with those in the PCB-only group. This study indicates that dietary vitamin A can improve the antioxidant capacity, immune response, detoxification enzymes activities, energy metabolism and hepatopancreas tissue structure of Chinese mitten crab fed PCB contaminated diets.

Dynamic repression by BCL6 controls the genome-wide liver response to fasting and steatosis

Transcription is tightly regulated to maintain energy homeostasis during periods of feeding or fasting, but the molecular factors that control these alternating gene programs are incompletely understood. Here, we find that the B cell lymphoma 6 (BCL6) repressor is enriched in the fed state and converges genome-wide with PPARα to potently suppress the induction of fasting transcription. Deletion of hepatocyte Bcl6 enhances lipid catabolism and ameliorates high-fat-diet-induced steatosis. In Ppara-null mice, hepatocyte Bcl6 ablation restores enhancer activity at PPARα-dependent genes and overcomes defective fasting-induced fatty acid oxidation and lipid accumulation. Together, these findings identify BCL6 as a negative regulator of oxidative metabolism and reveal that alternating recruitment of repressive and activating transcription factors to shared cis-regulatory regions dictates hepatic lipid handling.

Genome-wide Analysis Reveals DNA Methylation Alterations in Obesity Associated with High Risk of Colorectal Cancer

Obesity is a high risk factor for colorectal cancer (CRC). The contribution of underlying epigenetic mechanisms to CRC and the precise targets of epigenetic alterations during cancer development are largely unknown. Several types of epigenetic processes have been described, including DNA methylation, histone modification, and microRNA expression. To investigate the relationship between obesity and CRC, we studied both obese and CRC patients, focusing on genome-wide peripheral blood DNA methylation alterations. Our results show abnormal distributions of overlapping differentially methylated regions (DMRs) such as hypermethylated CpG islands, which may account for epigenetic instability driving cancer initiation in obesity patients. Furthermore, functional analysis suggests that altered DNA methylation of extracellular (e.g., O-glycan processing) and intracellular components contribute to activation of oncogenes (e.g. KRAS and SCL2A1) and suppression of tumor suppressors (e.g. ARHGEF4, EPHB2 and SOCS3), leading to increased oncogenic potency. Our study demonstrates how DNA methylation changes in obesity contribute to CRC development, providing direct evidence of an association between obesity and CRC. It also reveals the diagnostic potential of using DNA methylation as an early risk evaluation to detect patients with high risk for CRC.

Nutritional and lipidomics biomarkers of docosahexaenoic acid-based multivitamin therapy in pediatric NASH

Two recent randomized controlled trials demonstrated improved radiographic, histological and hepatometabolic cues of non-alcoholic steatohepatitis (NASH) in pediatric patients treated with the ω-3 fatty acid docosahexaenoic acid (DHA) in combination with vitamin D (VD) or with choline (CHO) and vitamin E (VE), the DHA-VD and DHA-CHO-VE trials, respectively). In the present study we verified the nutritional compliance to these DHA-based multivitamin treatments; lipidomics biomarkers of the reported outcome on NASH indicators were also investigated. Samples were obtained from 30 biopsy-proven pediatric NASH patients of the DHA-CHO-VE trial randomized in multivitamin treatment group and placebo group (n = 15 each), and from 12 patients of the treatment group of the DHA-VD trial. All patients underwent 6-month therapy plus 6 months of follow-up. Plasma samples and clinical data were obtained at baseline and at the end of the study (12 months). Selected biomarkers included the free form of DHA and other ω-3 fatty acid arachidonic acid (AA), indices of the vitamin E status, and some hepatic metabolites of these lipids. Radiographic and histological improvements of treated patients were associated with increased concentrations of DHA, α-linolenic acid and α-tocopherol (i.e. VE), and with decreased AA that was also investigated in complex lipids by untargetd lipidomics. As a result a significantly lowered AA/DHA ratio was observed to represent the main indicator of the response to the DHA-based therapy. Furthermore, baseline levels of AA/DHA showed strong association with NAS and US improvement. A stable correction of DHA AA metabolism interaction is associated with the curative effect of this therapy and may represent a key nutritional endpoint in the clinical management of pediatric NASH.

Increased plasma levels of the lipoperoxyl radical-derived vitamin E metabolite α-tocopheryl quinone are an early indicator of lipotoxicity in fatty liver subjects

Lipid peroxidation is one of the earliest pathogenic events of non-alcoholic fatty liver disease (NAFLD). In this context, an increased oxidation of the lipoperoxyl radical scavenger α-tocopherol (α-TOH) should occur already in the subclinical phases of the disease to compensate for the increase oxidation of the lipid excess of liver and possibly of other tissues. However, this assumption remains unsupported by direct analytical evidence. In this study, GC-MS/MS and LC-MS/MS procedures have been developed and applied for the first time to measure the vitamin E oxidation metabolite α-tocopheryl quinone (α-TQ) in plasma of fatty liver (FL) subjects that were compared in a pilot cross-sectional study with healthy controls. The protein adducts of 4-hydroxynonenal (4-HNE) and the free form of polyunsaturated free fatty acids (PUFA) were measured as surrogate indicators of lipid peroxidation. α-TQ formation was also investigated in human liver cells after supplementation with α-TOH and/or fatty acids (to induce steatosis). Compared with controls, FL subjects showed increased (absolute and α-TOH-corrected) levels of plasma α-TQ and 4-HNE, and decreased concentrations of PUFA. α-TQ levels positively correlated with indices of liver damage and metabolic dysfunction, such as alanine aminotransferase, bilirubin and triglycerides, and negatively correlated with HDL cholesterol. Fatty acid supplementation in human hepatocytes stimulated the generation of cellular oxidants and α-TOH uptake leading to increased α-TQ formation and secretion in the extracellular medium - both were markedly stimulated by α-TOH supplementation. In conclusion, plasma α-TQ represents an early biomarker of the lipoperoxyl radical-induced oxidation of vitamin E and lipotoxicity of the fatty liver.

A comprehensive transcriptome analysis of skeletal muscles in two Polish pig breeds differing in fat and meat quality traits

Pork is the most popular meat in the world. Unfortunately, the selection pressure focused on high meat content led to a reduction in pork quality. The present study used RNA-seq technology to identify metabolic process genes related to pork quality traits and fat deposition. Differentially expressed genes (DEGs) were identified between pigs of Pulawska and Polish Landrace breeds for two the most important muscles (semimembranosus and longissimus dorsi). A total of 71 significant DEGs were reported: 15 for longissimus dorsi and 56 for semimembranosus muscles. The genes overexpressed in Pulawska pigs were involved in lipid metabolism (APOD, LXRA, LIPE, AP2B1, ENSSSCG00000028753 and OAS2) and proteolysis (CST6, CTSD, ISG15 and UCHL1). In Polish Landrace pigs, genes playing a role in biological adhesion (KIT, VCAN, HES1, SFRP2, CDH11, SSX2IP and PCDH17), actin cytoskeletal organisation (FRMD6, LIMK1, KIF23 and CNN1) and calcium ion binding (PVALB, CIB2, PCDH17, VCAN and CDH11) were transcriptionally more active. The present study allows for better understanding of the physiological processes associated with lipid metabolism and muscle fiber organization. This information could be helpful in further research aiming to estimate the genetic markers.

Role of 3-Hydroxy Fatty Acid-Induced Hepatic Lipotoxicity in Acute Fatty Liver of Pregnancy

Acute fatty liver of pregnancy (AFLP), a catastrophic illness for both the mother and the unborn offspring, develops in the last trimester of pregnancy with significant maternal and perinatal mortality. AFLP is also recognized as an obstetric and medical emergency. Maternal AFLP is highly associated with a fetal homozygous mutation (1528G>C) in the gene that encodes for mitochondrial long-chain hydroxy acyl-CoA dehydrogenase (LCHAD). The mutation in LCHAD results in the accumulation of 3-hydroxy fatty acids, such as 3-hydroxy myristic acid, 3-hydroxy palmitic acid and 3-hydroxy dicarboxylic acid in the placenta, which are then shunted to the maternal circulation leading to the development of acute liver injury observed in patients with AFLP. In this review, we will discuss the mechanistic role of increased 3-hydroxy fatty acid in causing lipotoxicity to the liver and in inducing oxidative stress, mitochondrial dysfunction and hepatocyte lipoapoptosis. Further, we also review the role of 3-hydroxy fatty acids in causing placental damage, pancreatic islet β-cell glucolipotoxicity, brain damage, and retinal epithelial cells lipoapoptosis in patients with LCHAD deficiency.

Kidney Androgen-Regulated Protein (KAP) Transgenic Mice Are Protected Against High-Fat Diet Induced Metabolic Syndrome

Metabolic Syndrome (MS) is reaching epidemic proportions with significant social and economical burden worldwide. Since the molecular basis of MS remains poorly defined, we investigated the impact of KAP, a kidney specific androgen-regulated gene, in the development of high fat-diet (hfd)-induced MS. Tg mice overexpressing KAP specifically in proximal tubule cells of the kidney exhibited reduced body weight and lower liver and adipose tissue weight compared to control littermates when fed a hfd. KAP Tg mice showed diminished adipocyte hypertrophy and reduced hepatic steatosis, significantly correlating with expression of relevant molecular markers and lower lipid content in liver. KAP transgenic were protected from hfd-induced insulin resistance, increased blood pressure and exhibited lower IL-6 serum levels and diminished expression of inflammatory markers in the adipose. Moreover, KAP was localized in the secretory pathway of proximal tubule cells and it is released to the extracellular media, preventing IL-6 induction and STAT-3 activation upon TNFα stimulation. We conclude that KAP, which might act as a hormone-like product in extra-renal tissues, protects Tg mice against hfd-induced MS by preventing inflammatory related events that are mediated, in part, through the IL-6 pathway.

Cytochrome P450-2E1 is involved in aging-related kidney damage in mice through increased nitroxidative stress

The aim of this study was to investigate the role of cytochrome P450-2E1 (CYP2E1) in aging-dependent kidney damage since it is poorly understood. Young (7 weeks) and aged female (16-17 months old) wild-type (WT) and Cyp2e1-null mice were used. Kidney histology showed that aged WT mice exhibited typical signs of kidney aging such as cell vacuolation, inflammatory cell infiltration, cellular apoptosis, glomerulonephropathy, and fibrosis, along with significantly elevated levels of renal TNF-α and serum creatinine than all other groups. Furthermore, the highest levels of renal hydrogen peroxide, protein carbonylation and nitration were observed in aged WT mice. These increases in the aged WT mice were accompanied by increased levels of iNOS and mitochondrial nitroxidative stress through altered amounts and activities of the mitochondrial complex proteins and significantly reduced levels of the antioxidant glutathione (GSH). In contrast, the aged Cyp2e1-null mice exhibited significantly higher antioxidant capacity with elevated heme oxygenase-1 and catalase activities compared to all other groups, while maintaining normal GSH levels with significantly less mitochondrial nitroxidative stress compared to the aged WT mice. Thus, CYP2E1 is important in causing aging-related kidney damage most likely through increasing nitroxidative stress and that CYP2E1 could be a potential target in preventing aging-related kidney diseases.

Nonalcoholic fatty liver disease impairs the cytochrome P-450-dependent metabolism of α-tocopherol (vitamin E)

This study aims to investigate in in vivo and in vitro models of nonalcoholic fatty liver disease (NAFLD) the enzymatic metabolism of α-tocopherol (vitamin E) and its relationship to vitamin E-responsive genes with key role in the lipid metabolism and detoxification of the liver. The experimental models included mice fed a high-fat diet combined or not with fructose (HFD+F) and HepG2 human hepatocarcinoma cells treated with the lipogenic agents palmitate, oleate or fructose. CYP4F2 protein, a cytochrome P-450 isoform with proposed α-tocopherol ω-hydroxylase activity, decreased in HFD and even more in HFD+F mice liver; this finding was associated with increased hepatic levels of α-tocopherol and decreased formation of the corresponding long-chain metabolites α-13-hydroxy and α-13-carboxy chromanols. A decreased expression was also observed for PPAR-γ and SREBP-1 proteins, two vitamin E-responsive genes with key role in lipid metabolism and CYP4F2 gene regulation. A transient activation of CYP4F2 gene followed by a repression response was observed in HepG2 cells during the exposure to increasing levels of the lipogenic and cytotoxic agent palmitic acid; such gene repression effect was further exacerbated by the co-treatment with oleic acid and α-tocopherol and was also observed for PPAR-γ and the SREBP isoforms 1 and 2. Such gene response was associated with increased uptake and ω-hydroxylation of α-tocopherol, which suggests a minor role of CYP4F2 in the enzymatic metabolism of vitamin E in HepG2 cells. In conclusion, the liver metabolism and gene response of α-tocopherol are impaired in experimental NAFLD.

Nrf2 is crucial for the down-regulation of Cyp7a1 induced by arachidonic acid in Hepg2 cells

In former research, cyp7a1 expression was decreased but Nrf2 transcription and hepatic arachidonic acid (AA) concentration were increased in high-fat diet fed mice. This study aims to investigate the influence of AA in CYP7A1 expression and the role of Nrf2 in regulating CYP7A1 in the process. HepG2 cells were administered with different concentrations of AA. Nrf2 and CYP7A1 expressions were analyzed by real-time PCR and western blot. Nrf2 silenced and over-expressed cell models were constructed by Nrf2 siRNA and eukaryotic expression vector transient transfections and were used to investigate the role of Nrf2 in regulating CYP7A1 following AA administration. The results showed that Nrf2 was increased dose-dependently but CYP7A1 was decreased dose-dependently in cells treated with increasing concentrations of AA. The expression of CYP7A1 was increased by Nrf2 silence and was decreased by Nrf2 over-expression in HepG2 cells treated with different concentrations of AA. In conclusion, Nrf2 plays a significant role in the down-regulation of CYP7A1 induced by AA in HepG2 cells.