Phenotypic Alteration of Hepatocytes in Non-Alcoholic Fatty Liver Disease

Paricalcitol attenuates oxidative stress and inflammatory response in the liver of NAFLD rats by regulating FOXO3a and NFκB acetylation

The lack of therapeutics along with complex pathophysiology made non-alcoholic fatty liver disease (NAFLD) a research hotspot. Studies showed that the deficiency of Vitamin D plays a vital role in NAFLD pathogenesis. While several research studies focused on vitamin D supplementation in NAFLD, there is still a need to understand the regulatory mechanism of direct vitamin D receptor activation in NAFLD. In the present study, we explored the role of direct Vitamin D receptor activation using paricalcitol in choline-deficient high-fat diet-induced NAFLD rat liver and its modulation on protein acetylation. Our results showed that paricalcitol administration significantly reduced the fat accumulation in HepG2 cells and the liver of NAFLD rats. Paricalcitol attenuated the elevated serum level of alanine transaminase, aspartate transaminase, insulin, low-density lipoprotein, triglyceride, and increased high-density lipoprotein in NAFLD rats. Paricalcitol significantly decreased the increased total protein acetylation by enhancing the SIRT1 and SIRT3 expression in NAFLD liver. Further, the study revealed that paricalcitol reduced the acetylation of NFκB and FOXO3a in NAFLD liver along with a decrease in the mRNA expression of IL1β, NFκB, TNFα, and increased catalase and MnSOD. Moreover, total antioxidant activity, glutathione, and catalase were also elevated, whereas lipid peroxidation, myeloperoxidase, and reactive oxygen species levels were significantly decreased in the liver of NAFLD after paricalcitol administration. The study concludes that the downregulation of SIRT1 and SIRT3 in NAFLD liver was associated with an increased acetylated NFκB and FOXO3a. Paricalcitol effectively reversed hepatic inflammation and oxidative stress in NAFLD rats through transcriptional regulation of NFκB and FOXO3a, respectively, by inhibiting their acetylation.

Chlorogenic Acid and its Isomers Attenuate NAFLD by Mitigating Lipid Accumulation in Oleic Acid-Induced HepG2 Cells and High-Fat Diet- Fed Zebrafish

Chlorogenic acid (Chl), isochlorogenic acid A (Isochl A), and isochlorogenic acid B (Isochl B) are naturally occurring phenolic compounds, which have been shown to exert a regulatory effect on lipid metabolism. However, the mechanism underlying this effect remains unclear. Herein, we investigated the inhibitory effects and underlying mechanisms of these three phenolic compounds on oleic acid (OA)-induced HepG2 cells and high-fat diet (HFD)-fed zebrafish. Lipid accumulation and triacylglycerol levels increased in OA-induced cells, which was attenuated by Chl, Isochl A, and Isochl B. Moreover, the levels of malondialdehyde (MDA) and reactive oxygen species (ROS) decreased, while superoxide dismutase (SOD) levels increased by Chl, Isochl A and Isochl B treatment. Western blot analysis demonstrated that Chl, Isochl A and Isochl B reduced the expression of lipogenesis-related protein, including fatty acid synthase (FAS), acetyl-CoA carboxylase (ACC) and peroxisome proliferator-activated receptor gamma (PPARγ). Moreover, peroxisome proliferator-activated receptor alpha gamma (PPARα) was increased by Chl, Isochl A, and Isochl B treatment. In addition, our results indicated that Chl, Isochl A and Isochl B decreased lipid profiles and lipid accumulation in HFD-fed zebrafish. Thus, these findings highlight the potential of Chl, Isochl A, and Isochl B as effective agents for treating or/and ameliorating non-alcoholic fatty liver disease (NAFLD).

Adipocyte-derived exosomes from obstructive sleep apnoea rats aggravate MASLD by TCONS_00039830/miR-455-3p/Smad2 axis

A correlation exists between obstructive sleep apnoea (OSA) and the severity of metabolic dysfunction-associated steatotic liver disease (MASLD), OSA can induce more severe MASLD. However, the underlying regulatory mechanism between the two is unclear. To this end, this study explored the role and possible molecular mechanisms of adipocyte-derived exosomes under OSA in aggravating MASLD. Through sequencing technology, miR-455-3p was identified as a co-differentially expressed miRNA between the MASLD + OSA and Control groups and between the MASLD + OSA and MASLD groups. Upregulation of TCONS-00039830 and Smad2 and downregulation of miR-455-3p in the MASLD and MASLD + OSA groups were validated in vivo and in vitro. TCONS-00039830, as a differentially expressed LncRNA in exosomes found in the sequencing results, transfection notably downregulated miR-455-3p and upregulated Smad2 in hepatocytes. TCONS_00039830 overexpression increased fat, triglyceride and cholesterol levels, while miR-455-3p overexpression decreased these levels. Furthermore, exosome administration promoted the accumulation of fat, triglyceride and cholesterol, upregulated TCONS_00039830 and Smad2, and downregulated miR-455-3p. Overexpression of miR-455-3p reversed the increased fat accumulation and upregulated TCONS_00039830 and Smad2. In conclusion, OSA-derived exosomes promoted hepatocyte steatosis by regulating TCONS_00039830/miR-455-3p/Smad2 axis, thereby aggravating liver damage in MASLD.

The role of SPARC (secreted protein acidic and rich in cysteine) in the pathogenesis of obesity, type 2 diabetes, and non-alcoholic fatty liver disease

Secreted protein acidic and rich in cysteine (SPARC) is an extracellular matrix glycoprotein with pleiotropic functions, which is expressed in adipose, hepatic, muscular, and pancreatic tissue. Particularly, several studies demonstrated that SPARC is an important player in the context of obesity, diabetes, and fatty liver disease including advanced hepatic fibrosis and hepatocellular carcinoma. Evidence in murine and human samples indicates that SPARC is involved in adipogenesis, cellular metabolism, extracellular matrix modulation, glucose and lipid metabolism, among others. Furthermore, studies in SPARC knockout mouse model showed that SPARC contributes to adipose tissue formation, non-alcoholic fatty liver disease (NAFLD), and diabetes. Hence, SPARC may represent a novel and interesting target protein for future therapeutic interventions or a biomarker of disease progression. This review summarizes the role of SPARC in the pathophysiology of obesity, and extensively revised SPARC functions in physiological and pathological adipose tissue deposition, muscle metabolism, liver, and diabetes-related pathways.

Cellular heterogeneity and plasticity during NAFLD progression

Nonalcoholic fatty liver disease (NAFLD) is a progressive liver disease that can progress to nonalcoholic steatohepatitis (NASH), NASH-related cirrhosis, and hepatocellular carcinoma (HCC). NAFLD ranges from simple steatosis (or nonalcoholic fatty liver [NAFL]) to NASH as a progressive form of NAFL, which is characterized by steatosis, lobular inflammation, and hepatocellular ballooning with or without fibrosis. Because of the complex pathophysiological mechanism and the heterogeneity of NAFLD, including its wide spectrum of clinical and histological characteristics, no specific therapeutic drugs have been approved for NAFLD. The heterogeneity of NAFLD is closely associated with cellular plasticity, which describes the ability of cells to acquire new identities or change their phenotypes in response to environmental stimuli. The liver consists of parenchymal cells including hepatocytes and cholangiocytes and nonparenchymal cells including Kupffer cells, hepatic stellate cells, and endothelial cells, all of which have specialized functions. This heterogeneous cell population has cellular plasticity to adapt to environmental changes. During NAFLD progression, these cells can exert diverse and complex responses at multiple levels following exposure to a variety of stimuli, including fatty acids, inflammation, and oxidative stress. Therefore, this review provides insights into NAFLD heterogeneity by addressing the cellular plasticity and metabolic adaptation of hepatocytes, cholangiocytes, hepatic stellate cells, and Kupffer cells during NAFLD progression.

Hepatic Alarmins and Mitochondrial Dysfunction under Residual Hyperlipidemic Stress Lead to Irreversible NAFLD

BACKGROUND AND AIMS

Nonalcoholic fatty liver disease (NAFLD) includes a range of progressive disorders generated by excess lipid accumulation in the liver leading to hepatic steatosis and eventually fibrosis. We aimed to identify by high performance mass spectrometry-based proteomics the main signaling pathways and liver proteome changes induced by hypercholesterolemia in a rabbit atherosclerotic model that induced high accumulation of lipids in the liver.

METHODS

The effect of combined lipid-lowering drugs (statins and anti-PCSK9 monoclonal antibody) were used after the interruption of the hypercholesterolemic diet to identify also the potential mediators, such as alarmins, responsible for the irreversible NAFLD build up under the hyperlipidemic sustained stress.

RESULTS

Proteomic analysis revealed a number of proteins whose abundance was altered. They were components of metabolic pathways including fatty-acid degradation, glycolysis/gluconeogenesis, and nonalcoholic fatty liver disease. Mitochondrial dysfunction indicated alteration at the mitochondrial respiratory chain level and down-regulation of NADH: ubiquinone oxidoreductase. The expression of a majority of cytochromes (P4502E1, b5, and c) were up-regulated by lipid-lowering treatment. Long-term hyperlipidemic stress, even with a low-fat diet and lipid-lowering treatment, was accompanied by alarmin release (annexins, galectins, HSPs, HMGB1, S100 proteins, calreticulin, and fibronectin) that generated local inflammation and induced liver steatosis and aggressive fibrosis (by high abundance of galectin 3, fibronectin, and calreticulin).

CONCLUSIONS

The novel findings of this study were related to the residual effects of hyperlipidemic stress with consistent, combined lipid-lowering treatment with statin and inhibitor of PCSK9.

Cardiac Hepatopathy: New Perspectives on Old Problems through a Prism of Endogenous Metabolic Regulations by Hepatokines

Cardiac hepatopathy refers to acute or chronic liver damage caused by cardiac dysfunction in the absence of any other possible causative reasons of liver injury. There is a large number of evidence of the fact that cardiac hepatopathy is associated with poor clinical outcomes in patients with acute or actually decompensated heart failure (HF). However, the currently dominated pathophysiological background does not explain a role of metabolic regulative proteins secreted by hepatocytes in progression of HF, including adverse cardiac remodeling, kidney injury, skeletal muscle dysfunction, osteopenia, sarcopenia and cardiac cachexia. The aim of this narrative review was to accumulate knowledge of hepatokines (adropin; fetuin-A, selenoprotein P, fibroblast growth factor-21, and alpha-1-microglobulin) as adaptive regulators of metabolic homeostasis in patients with HF. It is suggested that hepatokines play a crucial, causative role in inter-organ interactions and mediate tissue protective effects counteracting oxidative stress, inflammation, mitochondrial dysfunction, apoptosis and necrosis. The discriminative potencies of hepatokines for HF and damage of target organs in patients with known HF is under on-going scientific discussion and requires more investigations in the future.

Nonalcoholic fatty liver disease in inflammatory arthritis: Relationship with cardiovascular risk

Liver disease is one of the most important causes of morbidity and mortality worldwide whose prevalence is dramatically increasing. The first sign of hepatic damage is inflammation which could be accompanied by the accumulation of fat called non-alcoholic fatty liver disease (NAFLD), causing damage in the hepatocytes. This stage can progress to fibrosis where the accumulation of fibrotic tissue replaces healthy tissue reducing liver function. The next stage is cirrhosis, a late phase of fibrosis where a high percentage of liver tissue has been replaced by fibrotic tissue and liver functionality is substantially impaired. There is a close interplay of cardiovascular disease (CVD) and hepatic alterations, where different mechanisms mediating this relation between the liver and systemic vasculature have been described. In chronic inflammatory diseases such as rheumatoid arthritis (RA) and psoriatic arthritis (PsA), in which the CVD risk is high, hepatic alterations seem to be more prevalent compared to the general population and other rheumatic disorders. The pathogenic mechanisms involved in the development of this comorbidity are still unraveled, although chronic inflammation, autoimmunity, treatments, and metabolic deregulation seem to have an important role. In this review, we will discuss the involvement of liver disease in the cardiovascular risk associated with inflammatory arthritis, the pathogenic mechanisms, and the recognized factors involved. Likewise, monitoring of the liver disease risk in routine clinical practice through both, classical and novel techniques and indexes will be exposed. Finally, we will examine the latest controversies that have been raised about the effects of the current therapies used to control the inflammation in RA and PsA, in the liver damage of those patients, such as methotrexate, leflunomide or biologics.

Persimmon Proanthocyanidins with Different Degrees of Polymerization Possess Distinct Activities in Models of High Fat Diet Induced Obesity

Proanthocyanidins is a kind of polyphenol that had been found with strong prevention ability on high fat diet induced obesity. However, whether proanthocyanidins with different polymerization degree showed different anti-obesity ability is unclear. Therefore, in this study, the effects of persimmon proanthocyanidins (P-PCs) and persimmon oligo-proanthocyanidins (P-OPCs) on high-fat diet induced obesity were systematically investigated. The findings indicated that both of P-PCs and P-OPCs significantly reduced the body weight, and P-PCs showed stronger anti-obesity ability compared with P-OPCs, P-OPCs seemed with stronger ability on improvement of insulin resistance. Furthermore, gut microbiota results indicated that the composition of the gut microbiota was changed after P-PCs and P-OPCs intervention in C57BL/6J mice. In addition, P-PCs exhibited strong inhibitory on the digestion of starch and fat. Above all, this study indicated that P-PCs showed stronger anti-obesity ability compared with P-OPCs.

Antioxidant Therapy Significantly Attenuates Hepatotoxicity following Low Dose Exposure to Microcystin-LR in a Murine Model of Diet-Induced Non-Alcoholic Fatty Liver Disease

We have previously shown in a murine model of Non-alcoholic Fatty Liver Disease (NAFLD) that chronic, low-dose exposure to the Harmful Algal Bloom cyanotoxin microcystin-LR (MC-LR), resulted in significant hepatotoxicity including micro-vesicular lipid accumulation, impaired toxin metabolism as well as dysregulation of the key signaling pathways involved in inflammation, immune response and oxidative stress. On this background we hypothesized that augmentation of hepatic drug metabolism pathways with targeted antioxidant therapies would improve MC-LR metabolism and reduce hepatic injury in NAFLD mice exposed to MC-LR. We chose N-acetylcysteine (NAC, 40 mM), a known antioxidant that augments the glutathione detoxification pathway and a novel peptide (pNaKtide, 25 mg/kg) which is targeted to interrupting a specific Src-kinase mediated pro-oxidant amplification mechanism. Histological analysis showed significant increase in hepatic inflammation in NAFLD mice exposed to MC-LR which was attenuated on treatment with both NAC and pNaKtide (both p ≤ 0.05). Oxidative stress, as measured by 8-OHDG levels in urine and protein carbonylation in liver sections, was also significantly downregulated upon treatment with both antioxidants after MC-LR exposure. Genetic analysis of key drug transporters including Abcb1a, Phase I enzyme-Cyp3a11 and Phase II metabolic enzymes-Pkm (Pyruvate kinase, muscle), Pklr (Pyruvate kinase, liver, and red blood cell) and Gad1 (Glutamic acid decarboxylase) was significantly altered by MC-LR exposure as compared to the non-exposed control group (all p ≤ 0.05). These changes were significantly attenuated with both pNaKtide and NAC treatment. These results suggest that MC-LR metabolism and detoxification is significantly impaired in the setting of NAFLD, and that these pathways can potentially be reversed with targeted antioxidant treatment.

Early SRC activation skews cell fate from apoptosis to senescence

Cells responding to DNA damage implement complex adaptive programs that often culminate in one of two distinct outcomes: apoptosis or senescence. To systematically identify factors driving each response, we analyzed human IMR-90 fibroblasts exposed to increasing doses of the genotoxin etoposide and identified SRC as a key kinase contributing early to this dichotomous decision. SRC was activated by low but not high levels of etoposide. With low DNA damage, SRC-mediated activation of p38 critically promoted expression of cell survival and senescence proteins, while SRC-mediated repression of p53 prevented a rise in proapoptotic proteins. With high DNA damage, failure to activate SRC led to elevation of p53, inhibition of p38, and apoptosis. In mice exposed to DNA damage, pharmacologic inhibition of SRC prevented the accumulation of senescent cells in tissues. We propose that inhibiting SRC could be exploited to favor apoptosis over senescence in tissues to improve health outcomes.

Clitorin ameliorates western diet-induced hepatic steatosis by regulating lipogenesis and fatty acid oxidation in vivo and in vitro

Nonalcoholic fatty liver disease (NAFLD) is usually correlated with metabolic diseases, such as obesity, insulin resistance, and hyperglycemia. Herein, we investigated the inhibitory effects and underlying governing mechanism of clitorin in a western diet (WD)-induced hepatic steatosis mouse model, and in oleic acid-stimulated HepG2 cells. Male C57BL/6 mice were fed a normal diet, WD, WD + 10 or 20 mg/kg orlistat, and WD + 10 or 20 mg/kg clitorin. HepG2 cells were treated with 1 mM oleic acid to induce lipid accumulation with or without clitorin. Clitorin significantly alleviated body weight gain and hepatic steatosis features (NAFLD activity score, micro-, and macro-vesicular steatosis) in WD-induced hepatic steatosis mice. Additionally, clitorin significantly decreased protein expressions of sterol regulatory element-binding protein 1 (SREBP1), peroxisome proliferator-activated receptor γ (PPARγ), and CCAAT/enhancer binding protein α (C/EBPα) in WD-induced hepatic steatosis mice. Moreover, clitorin significantly diminished the mRNA levels of SREBP1, acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS), and hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) and enhanced the mRNA levels of peroxisome proliferator-activated receptor α (PPARα) and carnitine palmitoyltranserase-1 (CTP-1), as well as adenosine monophosphate-activated protein kinase (AMPK) in the liver of WD-induced hepatic steatosis mice and oleic acid-stimulated HepG2 cells. Overall, our findings demonstrated that clitorin can be a potentially efficacious candidate for NAFLD management.

Dietary and Lifestyle Inflammation Scores Are Inversely Associated with Metabolic-Associated Fatty Liver Disease among Iranian Adults: A Nested Case-Control Study

BACKGROUND

Diet and lifestyle may affect risk for metabolic-associated fatty liver disease (MAFLD) by chronically elevating systemic inflammation.

OBJECTIVES

In this study we investigated the separate and joint associations of dietary and lifestyle inflammation scores (DIS and LIS, respectively) with MAFLD risk.

METHODS

For this nested case-control study we identified and recruited 968 patients with MAFLD (defined as having a fatty liver index ≥60 plus ≥1 of the following conditions: overweight or obese, type II diabetes mellitus, evidence of metabolic dysregulation) and 964 controls from among 35-70-y-old men and women in the baseline phase of the Sabzevar Persian Cohort Study. We collected demographic, lifestyle, anthropometric, biochemical, and dietary intake information (via a validated FFQ) from which we calculated a circulating inflammation biomarker-weighted, predominantly whole foods and beverages-based, 19-component DIS and a 3-component LIS. We estimated DIS- and LIS-MAFLD associations using multivariable unconditional logistic regression. We also calculated equal-weight DIS and LIS to capture all potential mechanisms (inflammation plus other mechanisms) for associations of diet and lifestyle with MAFLD risk.

RESULTS

Among those in the highest relative to the lowest DIS and LIS tertiles, the multivariable-adjusted ORs and their 95% CIs were OR: 1.84; 95% CI: 1.61, 2.07; Ptrend < 0.001, and OR: 1.96; 95% CI: 1.69, 2.21; Ptrend < 0.001, respectively. For those in the highest relative to the lowest joint DIS and LIS tertile, the values were OR: 2.56; 95% CI: 2.19, 2.93; Pinteraction < 0.001. The findings were similar by sex. The third tertile values for the equal-weight DIS- and LIS-MAFLD associations were OR: 1.87; 95% CI: 1.41, 2.34; and OR: 2.16; 95% CI: 1.85, 2.46, respectively.

CONCLUSIONS

Our results suggest that higher balances of pro- relative to anti-inflammatory dietary and lifestyle exposures, separately and especially jointly, may be associated with higher MAFLD risk among adults. Also, inflammation may be the primary mechanism through which diet affects MAFLD risk.

Extracellular vesicles released by steatotic hepatocytes alter adipocyte metabolism

The composition of extracellular vesicles (EVs) is altered in many pathological conditions, and their molecular content provides essential information on features of parent cells and mechanisms of crosstalk between cells and organs. Metabolic Syndrome (MetS) is a cluster of clinical manifestations including obesity, insulin resistance, dyslipidemia and hypertension that increases the risk of cardiovascular disease and type 2 diabetes mellitus. Here, we investigated the crosstalk between liver and adipocytes by characterizing EVs secreted by primary hepatocytes isolated from Zucker rat model, and studied the effect they have on 3T3-L1 adipocytes. We found that steatotic hepatocytes secrete EVs with significantly reduced exosomal markers in comparison with their lean counterpart. Moreover, proteomic analysis revealed that those EVs reflect the metabolic state of the parent cell in that the majority of proteins upregulated relate to fat metabolism, fatty acid synthesis, glycolysis, and pentose phosphate pathway. In addition, hepatocytes-secreted EVs influenced lipolysis and insulin sensitivity in recipient 3T3-L1 adipocytes. Untargeted metabolomic analysis detected alterations in different adipocyte metabolic pathways in cells treated with hepatic EVs. In summary, our work showed that steatosis has a significant impact in the amount and composition of EVs secreted by hepatocytes. Moreover, our data point to the involvement of hepatic-EVs in the development of pathologies associated with MetS.

Synbiotic goat milk kefir improves health status in rats fed a high-fat and high-fructose diet

Background and Aim:

Kefir, a natural probiotic containing bacteria and yeast, is a fermented milk product, whereas glucomannan from porang tuber (Amorphophallus oncophyllus) is prebiotic in vivo. Simvastatin is a potent lipid-lowering statin that can be utilized for pharmacological therapy in obesity. This study aimed to determine the effect of goat milk kefir supplemented with porang glucomannan (synbiotic kefir) and goat milk kefir without glucomannan (probiotic kefir) on blood glucose, hemoglobin A1c (HbA1c), free fatty acids (FFAs), tumor necrosis factor-alpha (TNF-α), gene expression of peroxisome proliferator-activated receptor gamma (PPARg), and insulin-producing cells in rats fed a high-fat and high-fructose (HFHF) diet.

Materials and Methods:

Male Sprague-Dawley rats were divided into five dietary groups: (1) Normal control, (2) rats fed HFHF, (3) rats fed HFHF+probiotic kefir, (4) rats fed HFHF+synbiotic kefir, and (5) rats fed HFHF+simvastatin. All of these treatments were administered for 4 weeks.

Results:

There were no significant differences in plasma glucose levels in HFHF diet-fed rats before and after treatment. However, plasma HbA1c and TNF-α decreased, and FFAs were inhibited in rats after treatment with synbiotic kefir. Synbiotic kefir decreased the gene expression of PPARγ2 in HFHF diet-fed rats but did not affect the total number of islets of Langerhans and insulin-producing cells.

Conclusion:

Synbiotic kefir improved the health of rats fed an HFHF diet by decreasing HbA1c, TNF-α, and PPARγ2 gene expression and preventing an increase in FFAs.

A retinoic acid receptor β2 agonist attenuates transcriptome and metabolome changes underlying nonalcohol-associated fatty liver disease

Nonalcohol-associated fatty liver disease (NAFLD) is characterized by excessive hepatic accumulation of fat that can progress to steatohepatitis, and currently, therapeutic options are limited. Using a high-fat diet (HFD) mouse model of NAFLD, we determined the effects of the synthetic retinoid, AC261066, a selective retinoic acid receptor β2 (RARβ2) agonist, on the global liver transcriptomes and metabolomes of mice with dietary-induced obesity (DIO) using genome-wide RNA-seq and untargeted metabolomics. We found that AC261066 limits mRNA increases in several presumptive NAFLD driver genes, including Pklr, Fasn, Thrsp, and Chchd6. Importantly, AC261066 limits the increases in the transcript and protein levels of KHK, a key enzyme for fructose metabolism, and causes multiple changes in liver metabolites involved in fructose metabolism. In addition, in cultured murine hepatocytes, where exposure to fructose and palmitate results in a profound increase in lipid accumulation, AC261066 limits this lipid accumulation. Importantly, we demonstrate that in a human hepatocyte cell line, RARβ is required for the inhibitory effects of AC261066 on palmitate-induced lipid accumulation. Finally, our data indicate that AC261066 inhibits molecular events underpinning fibrosis and exhibits anti-inflammatory effects. In conclusion, changes in the transcriptome and metabolome indicate that AC261066 affects molecular changes underlying multiple aspects of NAFLD, including steatosis and fibrosis. Therefore, we suggest that AC261066 may have potential as an effective therapy for NAFLD.

Ameliorative mechanisms of turmeric-extracted curcumin on arsenic (As)-induced biochemical alterations, oxidative damage, and impaired organ functions in rats

Arsenic (As) is known for its carcinogenic and hepatorenal toxic effects causing serious health problems in human beings. Turmeric (Curcuma longa L.) extracted curcumin (Cur) is a polyphenolic antioxidant which has ability to combat hazardous environmental toxicants. This study (28 days) was carried out to investigate the therapeutic efficacy of different doses of Cur (Cur: 80, 160, 240 mg kg^-1) against the oxidative damage in the liver and kidney of male rats caused by sodium arsenate (Na₃AsO₄) (10 mg L^-1). As exposure significantly elevated the values of organ index, markers of hepatic injury (i.e., alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP)) and renal functions (i.e., total bilirubin, urea and creatinine, total cholesterol, total triglycerides, and lipid peroxidation malondialdehyde (MDA)). Moreover, different antioxidant markers such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR) activities in the liver and kidney tissues were reduced after As-induced toxicity. However, Na₃AsO₄ induced histopathological changes in various organs were minimized after the treatment with Cur. The alleviation effect of Cur was dosage dependent with an order of 240>160>80 mg kg^-1. The oral administration of Cur prominently alleviated the As-induced toxicity in liver and kidney tissues by reducing lipid peroxidation, ALT, AST, ALP, total bilirubin, urea, creatinine, total cholesterol, total triglycerides, and low-density lipoproteins (LDL). In addition, Cur being an antioxidant improved defense system by enhancing activities of SOD, CAT, GPx, and GR. Overall, the findings explain the capability of Cur to counteract the oxidative alterations as well as hepatorenal injuries due to As intoxication.

Notoginsenoside Ft1 acts as a TGR5 agonist but FXR antagonist to alleviate high fat diet-induced obesity and insulin resistance in mice

Obesity and its associated complications are highly related to a current public health crisis around the world. A growing body of evidence has indicated that G-protein coupled bile acid (BA) receptor TGR5 (also known as Gpbar-1) is a potential drug target to treat obesity and associated metabolic disorders. We have identified notoginsenoside Ft1 (Ft1) from Panax notoginseng as an agonist of TGR5 in vitro. However, the pharmacological effects of Ft1 on diet-induced obese (DIO) mice and the underlying mechanisms are still elusive. Here we show that Ft1 (100 mg/100 diet) increased adipose lipolysis, promoted fat browning in inguinal adipose tissue and induced glucagon-like peptide-1 (GLP-1) secretion in the ileum of wild type but not Tgr5 -/- obese mice. In addition, Ft1 elevated serum free and taurine-conjugated bile acids (BAs) by antagonizing Fxr transcriptional activities in the ileum to activate Tgr5 in the adipose tissues. The metabolic benefits of Ft1 were abolished in Cyp27a1 -/- mice which have much lower BA levels. These results identify Ft1 as a single compound with opposite activities on two key BA receptors to alleviate high fat diet-induced obesity and insulin resistance in mice.

Pharmacological Properties of a Traditional Korean Formula Bojungchiseup-tang on 3T3-L1 Preadipocytes and High-Fat Diet-Induced Obesity Mouse Model

The global obesity epidemic has nearly doubled since 1980, and this increasing prevalence is threatening public health. It has been reported that natural products could contain potential functional ingredients that may assist in preventing obesity. Bojungchiseub-tang (BJT), mentioned in the Donguibogam as an herbal medication for the treatment of edema, a symptom of obesity, consists of eleven medicinal herbs. However, the pharmacological activity of BJT has not been investigated. The present study was designed to investigate the putative effect of BJT on the adipogenesis of 3T3-L1 cells and the weight gain of high-fat diet (HFD-) fed C57BL/6 mice. Oil Red O staining was conducted to examine the amount of lipids in 3T3-L1 adipocytes. Male C57BL/6 mice were divided into three groups: standard diet group (control, CON), 45% HFD group (HFD), and HFD supplemented with 10% of BJT (BJT). The expression levels of genes and proteins related to adipogenesis in cells, WAT, and liver were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR) and western blot, respectively. We found that BJT treatment significantly decreased the protein and mRNA levels of peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer-binding protein α (C/EBPα), and sterol regulatory element-binding protein 1 (SREBP1) in a dose-dependent manner in differentiated 3T3-L1 cells. Similar to the results of the in vitro experiment, BJT suppressed HFD-induced weight gain in an obese mouse model. In addition, BJT effectively reduced the HFD-induced epididymal adipose tissue weight/body weight index. BJT also downregulated the mRNA levels of PPARγ, C/EBPα, and SREBP1 in the epididymal adipose and liver tissue of HFD-fed obese mice. These findings suggest that BJT induces weight loss by affecting adipogenic transcription factors.

MiR-455 targeting SOCS3 improve liver lipid disorders in diabetic mice

MiR-455 has been verified a key regulator of brown adipose tissue and adipose tissue-specific overexpression of miR-455 (ap2-miR-455) mice could combat high-fat-diet-induced obesity. This study is to verify overexpression of miR-455 could ameliorate the lipid accumulation and metabolism in the liver of db/db diabetic mice and explore the potential mechanisms. Diabetic mice (db/db) and control mice (db/m) were randomly divided into four groups. After overexpression of miR-455 in the liver of db/db mice, the triglycerides level in both serum and liver decreased, the lipid deposit in liver was improved, the expression of fatty acid synthase, stearoyl-CoA desaturase 1, sterol regulatory element binding protein 1c (SREBP-1c) and acetyl-CoA carboxylase (ACCα) was also significantly down-regulated. TargetScan indicated that suppressor of cytokine signalling 3 (SOCS3) is predicated to target miR-455 and the protein of SOCS3 in the liver of db/db mice after intervention was significantly decreased. The dual luciferase reporter assay showed that SOCS3 was target gene of miR-455. In vitro, in Palmitate (PA)-stimulated human normal liver (LO2) cells, transfected miR-455 mimic could significantly inhibit the expression of SOCS3, while transfected miR-455 inhibitor could up-regulate the expression of SOCS3. Transfecting LO2 cells with siRNA of SOCS3 could significantly down-regulate the protein expression of SREBP-1c and ACCα. Our study showed that overexpression of miR-455 in the liver could improve lipid metabolism in diabetic mice by down-regulating its target gene SOCS3.

Modulation of Lipid Metabolism by Trans-Anethole in Hepatocytes

Non-alcoholic fatty liver disease is caused by excessive lipid accumulation in hepatocytes. Although trans-anethole (TAO) affects hypoglycemia and has anti-immune activity and anti-obesity effects, its role in non-alcoholic fatty liver disease remains unknown. This study aimed to evaluate the effects of TAO on cellular senescence, lipid metabolism, and reinforcement of microenvironments in HepG2 cells. To analyze the lipid metabolic activity of TAO, PCR analysis, flow-cytometry, and Oil Red O staining were performed, and mitochondrial membrane potential (MMP) and cellular senescence kits were used for assessing the suppression of cellular senescence. At 2000 μg/mL TAO, the cellular viability was approximately 99%, and cell senescence decreased dose-dependently. In the results for MMP, activity increased with concentration. The levels of lipolytic genes, CPT2, ACADS, and HSL, strongly increased over 3 days and the levels of lipogenic genes, ACC1 and GPAT, were downregulated on the first day at 1000 μg/mL TAO. Consequently, it was found that TAO affects the suppression of cellular senescence, activation of lipid metabolism, and reinforcement of the microenvironment in HepG2 cells, and can be added as a useful component to functional foods to prevent fatty liver disease and cellular senescence, as well as increase the immunoactivity of the liver.

Prolonged Lipid Accumulation in Cultured Primary Human Hepatocytes Rather Leads to ER Stress than Oxidative Stress

Overweight has become a major health care problem in Western societies and is accompanied by an increasing incidence and prevalence of non-alcoholic fatty liver disease (NAFLD). The progression from NAFLD to non-alcoholic steatohepatitis (NASH) marks a crucial tipping point in the progression of severe and irreversible liver diseases. This study aims to gain further insight into the molecular processes leading to the evolution from steatosis to steatohepatitis. Steatosis was induced in cultures of primary human hepatocytes by continuous five-day exposure to free fatty acids (FFAs). The kinetics of lipid accumulation, lipotoxicity, and oxidative stress were measured. Additionally, ER stress was evaluated by analyzing the protein expression profiles of its key players: PERK, IRE1a, and ATF6a. Our data revealed that hepatocytes are capable of storing enormous amounts of lipids without showing signs of lipotoxicity. Prolonged lipid accumulation did not create an imbalance in hepatocyte redox homeostasis or a reduction in antioxidative capacity. However, we observed an FFA-dependent increase in ER stress, revealing thresholds for triggering the activation of pathways associated with lipid stress, inhibition of protein translation, and apoptosis. Our study clearly showed that even severe lipid accumulation can be attenuated by cellular defenses, but regenerative capacities may be reduced.

Predicting Nonalcoholic Fatty Liver Disease through a Panel of Plasma Biomarkers and MicroRNAs in Female West Virginia Population

(1) Background: Nonalcoholic fatty liver disease (NAFLD) is primarily characterized by the presence of fatty liver, hepatic inflammation and fibrogenesis eventually leading to nonalcoholic steatohepatitis (NASH) or cirrhosis. Obesity and diabetes are common risk factors associated with the development and progression of NAFLD, with one of the highest prevalence of these diseased conditions in the West Virginia population. Currently, the diagnosis of NAFLD is limited to radiologic studies and biopsies, which are not cost-effective and highly invasive. Hence, this study aimed to develop a panel and assess the progressive levels of circulatory biomarkers and miRNA expression in patients at risk for progression to NASH to allow early intervention strategies. (2) Methods: In total, 62 female patients were enrolled and blood samples were collected after 8–10 h of fasting. Computed tomography was performed on abdomen/pelvis following IV contrast administration. The patients were divided into the following groups: Healthy subjects with normal BMI and normal fasting blood glucose (Control, n = 20), Obese with high BMI and normal fasting blood glucose (Obese, n = 20) and Obese with high fasting blood glucose (Obese + DM, n = 22). Based on findings from CT, another subset was created from Obese + DM group with patients who showed signs of fatty liver infiltration (Obese + DM(FI), n = 10). ELISA was performed for measurement of plasma biomarkers and RT-PCR was performed for circulating miRNA expression. (3) Results: Our results show significantly increased levels of plasma IL-6, Leptin and FABP-1, while significantly decreased level of adiponectin in Obese, Obese + DM and Obese + DM(FI) group, as compared to healthy controls. The level of CK-18 was significantly increased in Obese + DM(FI) group as compared to control. Subsequently, the expression of miR-122, miR-34a, miR-375, miR-16 and miR-21 was significantly increased in Obese + DM and Obese + DM(FI) group as compared to healthy control. Our results also show distinct correlation of IL-6, FABP-1 and adiponectin levels with the expression of miRNAs in relation to the extent of NAFLD progression. (4) Conclusion: Our results support the clinical application of these biomarkers and miRNAs in monitoring the progression of NAFLD, suggesting a more advanced diagnostic potential of this panel than conventional methods. This panel may provide an appropriate method for early prognosis and management of NAFLD and subsequent adverse hepatic pathophysiology, potentially reducing the disease burden on the West Virginia population.

Does adipose tissue inflammation drive the development of non-alcoholic fatty liver disease in obesity?

Obesity, an increasingly common problem in modern societies, is associated with acquired metabolic disturbances. In this perspective, the development of insulin resistance is now recognized to be initiated by inflammation of the adipose tissue, but the events that lead to this inflammation are still vague. Furthermore, visceral adipose tissue plays a significant role in obesity pathophysiology and in its clinical effects, such as non-alcoholic fatty liver disease (NAFLD). Among the possible mechanisms linking NAFLD and obesity, we focused on Visfatin/NAMPT, mostly produced by macrophages infiltrated in adipose tissue and a biomarker of the inflammatory cascade affecting hepatic inflammation in NAFLD. We also addressed the signalling pathway triggered by the binding of VEGF-B to its receptor, which mediates lipid fluxes throughout the body, being a promising target to prevent ectopic lipid accumulation. We reviewed the available literature on the topic and we suggest a crosstalk between adipose tissue inflammation and NAFLD in order to provide new insights about the putative mechanisms involved in the development of NAFLD in the obesity context. A better understanding of the pathophysiological processes underlying NAFLD will allow the development of new therapeutic approaches.

Therapeutic Efficacy of Antioxidants in Ameliorating Obesity Phenotype and Associated Comorbidities

Obesity has been a worldwide epidemic for decades. Despite the abundant increase in knowledge regarding the etiology and pathogenesis of obesity, the prevalence continues to rise with estimates predicting considerably higher numbers by the year 2030. Obesity is characterized by an abnormal lipid accumulation, however, the physiological consequences of obesity are far more concerning. The development of the obesity phenotype constitutes dramatic alterations in adipocytes, along with several other cellular mechanisms which causes substantial increase in systemic oxidative stress mediated by reactive oxygen species (ROS). These alterations promote a chronic state of inflammation in the body caused by the redox imbalance. Together, the systemic oxidative stress and chronic inflammation plays a vital role in maintaining the obese state and exacerbating onset of cardiovascular complications, Type II diabetes mellitus, dyslipidemia, non-alcoholic steatohepatitis, and other conditions where obesity has been linked as a significant risk factor. Because of the apparent role of oxidative stress in the pathogenesis of obesity, there has been a growing interest in attenuating the pro-oxidant state in obesity. Hence, this review aims to highlight the therapeutic role of antioxidants, agents that negate pro-oxidant state of cells, in ameliorating obesity and associated comorbidities. More specifically, this review will explore how various antioxidants target unique and diverse pathways to exhibit an antioxidant defense mechanism.

The offspring from rats fed a fatty diet display impairments in the activation of liver peroxisome proliferator activated receptor alpha and features of fatty liver disease

Maternal obesity programs liver derangements similar to those of NAFLD. Our main goal was to evaluate whether these liver anomalies were related to aberrant PPARα function. Obesity was induced in female Albino-Wistar rats by a fatty diet (FD rats). Several parameters related to NAFLD were evaluated in both plasma and livers from fetuses of 21 days of gestation and 140-day-old offspring. FD fetuses and offspring developed increased levels of AST and ALT, signs of inflammation and oxidative and nitrative stress-related damage. FD offspring showed dysregulation of Plin2, CD36, Cyp4A, Aco, Cpt-1, Hadha and Acaa2 mRNA levels, genes involved in lipid metabolism and no catabolic effect of the PPARα agonist clofibrate. These results suggest that the FD offspring is prone to develop fatty liver, a susceptibility that can be linked to PPARα dysfunction, and that this could in turn be related to the liver impairments programmed by maternal obesity.

Disrupting phosphatase SHP2 in macrophages protects mice from high-fat diet-induced hepatic steatosis and insulin resistance by elevating IL-18 levels

Chronic low-grade inflammation plays an important role in the pathogenesis of type 2 diabetes. Src homology 2 domain-containing tyrosine phosphatase-2 (SHP2) has been reported to play diverse roles in different tissues during the development of metabolic disorders. We previously reported that SHP2 inhibition in macrophages results in increased cytokine production. Here, we investigated the association between SHP2 inhibition in macrophages and the development of metabolic diseases. Unexpectedly, we found that mice with a conditional SHP2 knockout in macrophages (cSHP2-KO) have ameliorated metabolic disorders. cSHP2-KO mice fed a high-fat diet (HFD) gained less body weight and exhibited decreased hepatic steatosis, as well as improved glucose intolerance and insulin sensitivity, compared with HFD-fed WT littermates. Further experiments revealed that SHP2 deficiency leads to hyperactivation of caspase-1 and subsequent elevation of interleukin 18 (IL-18) levels, both in vivo and in vitro Of note, IL-18 neutralization and caspase-1 knockout reversed the amelioration of hepatic steatosis and insulin resistance observed in the cSHP2-KO mice. Administration of two specific SHP2 inhibitors, SHP099 and Phps1, improved HFD-induced hepatic steatosis and insulin resistance. Our findings provide detailed insights into the role of macrophagic SHP2 in metabolic disorders. We conclude that pharmacological inhibition of SHP2 may represent a therapeutic strategy for the management of type 2 diabetes.

Polysaccharides isolated from Cordyceps Sinensis contribute to the progression of NASH by modifying the gut microbiota in mice fed a high-fat diet

Various dietary fibers are considered to prevent obesity by modulating the gut microbiota. Cordyceps sinensis polysaccharide (CSP) is a soluble dietary fiber known to have protective effects against obesity and related diseases, but whether these effects induce any side effects remains unknown. The function and safety of CSP were tested in high-fat diet (HFD)-feding C57BL/6J mice. The results revealed that even though CSP supplementation could prevent an increase in body weight, it aggravated liver fibrosis and steatosis as evidenced by increased inflammation, lipid metabolism markers, insulin resistance (IR) and alanine aminotransferase (ALT) in HFD-induced obesity. 16S rDNA gene sequencing was used to analyze the gut microbiota composition, and the relative abundance of the Actinobacteria phylum, including the Olsenella genus, was significantly higher in CSP-treated mice than in HFD-fed mice. CSP supplementation may increase the proportion of Actinobacteria, which can degrade CSP. The high level of Actinobacteria aggravated the disorder of the intestinal flora and contributed to the progression from obesity to nonalcoholic steatohepatitis (NASH) and related diseases.

Activation of Liver X Receptors by GW3965 Attenuated Deoxycorticosterone Acetate-Salt Hypertension-Induced Cardiac Functional and Structural Changes

In this study, the effect of liver X receptor (LXR) activation on hypertension-induced cardiac structural and functional alterations was investigated. Hypertension was induced by deoxycorticosterone acetate (DOCA)-salt administration in uninephrectomized rats for 6 weeks. LXR agonist GW3965 (3-{3-[(2-chloro-3-trifluoromethyl-benzyl)-(2,2-diphenyl-ethyl)-amino]-propoxy}-phenyl)-acetic acid was given for the past week. Rhythmic activity and contractions of the isolated heart tissues were recorded. Biochemical parameters were assessed in ventricular tissue and plasma samples. Cardiac expressions of various proteins were examined, and histopathological evaluation was performed in the left ventricle and liver. GW3965 reduced systolic blood pressure and enhanced noradrenaline-stimulated papillary muscle contraction induced by DOCA-salt + uninephrectomy. Plasma and tissue total antioxidant capacity (TAC) increased and tissue 4-hydroxynonenal (4-HNE) levels decreased in the DOCA-salt group. GW3965 elevated plasma and tissue TAC levels in both of groups. Glucose-regulated protein-78 (GRP78), phospho-dsRNA-activated-protein kinase-like ER kinase (p-PERK), matrix metalloproteinase-2 (MMP-2), and nuclear factor-κB p65 (NF-κB p65) expression was augmented, and inhibitor-κB-α (IκB-α) expression was reduced in hypertensive hearts. The altered levels of all these markers were reversed by GW3965. Also, GW3965 ameliorated DOCA-salt + uninephrectomy-induced cardiac and hepatic inflammation and fibrosis. However, GW3965 unchanged the plasma lipid levels and hepatic balloon degeneration score. These results demonstrated that LXR activation may improve hypertension-induced cardiac changes without undesired effects.

Obeticholic acid for the treatment of nonalcoholic steatohepatitis

INTRODUCTION

NAFLD has grown to become the most prevalent liver disease in the world, with a quarter of the general population estimated to have the disease. NASH, characterized as NAFLD with inflammation, is associated with worsening fibrosis along with increased incidence of HCC. Despite high prevalence of this disease, no pharmacologic treatments approved by regulatory agencies are available.

AREAS COVERED

This review briefly discusses present understanding of NASH pathology and currently available treatments. We also discuss data on the role of OCA as an FXR agonist in modulating disease in NASH. A comprehensive literature search of review articles, original research articles, and prospective clinical trials from 1998 to the present was performed.

EXPERT OPINION

Based on 18-month interim findings of the REGENERATE trial, OCA likely improves fibrosis in NASH and therefore may have a beneficial effect in delaying or even preventing cirrhosis. The side effect of an atherogenic lipoprotein profile may adversely affect long-term outcomes, though studies have shown that co-administration of statins is able to mitigate this effect. OCA is likely to become an option for treatment, but the specific context within which it may be prescribed still needs to be clarified.

Emergent Properties of the HNF4α-PPARγ Network May Drive Consequent Phenotypic Plasticity in NAFLD

Non-alcoholic fatty liver disease (NAFLD) is the most common form of chronic liver disease in adults and children. It is characterized by excessive accumulation of lipids in the hepatocytes of patients without any excess alcohol intake. With a global presence of 24% and limited therapeutic options, the disease burden of NAFLD is increasing. Thus, it becomes imperative to attempt to understand the dynamics of disease progression at a systems-level. Here, we decoded the emergent dynamics of underlying gene regulatory networks that were identified to drive the initiation and the progression of NAFLD. We developed a mathematical model to elucidate the dynamics of the HNF4α-PPARγ gene regulatory network. Our simulations reveal that this network can enable multiple co-existing phenotypes under certain biological conditions: an adipocyte, a hepatocyte, and a "hybrid" adipocyte-like state of the hepatocyte. These phenotypes may also switch among each other, thus enabling phenotypic plasticity and consequently leading to simultaneous deregulation of the levels of molecules that maintain a hepatic identity and/or facilitate a partial or complete acquisition of adipocytic traits. These predicted trends are supported by the analysis of clinical data, further substantiating the putative role of phenotypic plasticity in driving NAFLD. Our results unravel how the emergent dynamics of underlying regulatory networks can promote phenotypic plasticity, thereby propelling the clinically observed changes in gene expression often associated with NAFLD.

Organ crosstalk: the potent roles of inflammation and fibrotic changes in the course of organ interactions

BACKGROUND

Organ crosstalk can be defined as the complex and mutual biological communication between distant organs mediated by signaling factors. Normally, crosstalk helps to coordinate and maintain homeostasis, but sudden or chronic dysfunction in any organ causes dysregulation in another organ. Many signal molecules, including cytokines and growth factors, are involved in the metabolic dysregulation, and excessive or inappropriate release of these molecules leads to organ dysfunction or disease (e.g., obesity, type 2 diabetes).

AIM AND METHOD

The aim of this review is to reveal the impact of organ crosstalk on the pathogenesis of diseases associated with organ interactions and the role of inflammatory and fibrotic changes in the organ dysfunction. After searching in MEDLINE, PubMed and Google Scholar databases using 'organ crosstalk' as a keyword, studies related to organ crosstalk and organ interaction were compiled and examined.

CONCLUSION

The organ crosstalk and the functional integration of organ systems are exceedingly complex processes. Organ crosstalk contributes to metabolic homeostasis and affects the inflammatory response, related pathways and fibrotic changes. As in the case of interactions between adipose tissue and intestine, stimulation of inflammatory mechanisms plays an active role in the development of diseases including insulin resistance, obesity, type 2 diabetes and hepatic steatosis. The increased level of knowledge about the 'crosstalk' between any organ and distant organs will facilitate the early diagnosis of the disease as well as the management of the treatment practices in the short- and long-term organ dysfunction.