Obesity and nonalcoholic fatty liver disease: current perspectives

Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of the Novel Non-Bile Acid FXR Agonist Tropifexor (LJN452) in Healthy Volunteers

Tropifexor (LJN452) is a potent, orally available, non–bile acid farnesoid X receptor agonist under clinical development for chronic liver diseases. Here, we present results from a first‐in‐human study of tropifexor following single‐ and multiple‐ascending doses (SAD/MAD) and food effect substudy in healthy volunteers. The SAD study included 6 fasted cohorts receiving 10‐ to 3000‐µg tropifexor or placebo and 1 cohort receiving 300‐µg tropifexor with a high‐fat meal. The MAD study included 4 lean cohorts receiving 10 to 100 µg and 1 obese cohort receiving 30‐µg once‐daily doses or placebo for 14 days. Pharmacodynamic assessment of fibroblast growth factor 19 and fasting plasma lipids was performed after dosing. Overall, 95 volunteers received at least 1 tropifexor or placebo dose. Tropifexor was well tolerated up to 3000 µg and 100 µg in the SAD and MAD studies, respectively; however, 2 subjects discontinued the MAD study due to asymptomatic elevation of liver transaminases. At single doses, tropifexor showed a moderate rate of absorption (median time to maximum concentration, 4 hours), dose‐proportional increases in exposure, and elimination half‐life of 13.5 to 21.9 hours. When taken with food, tropifexor exposure increased by ∼60%. With multiple dosing, steady state was reached on day 4 with <2‐fold accumulation. Single and multiple doses showed dose‐dependent increases in fibroblast growth factor 19. No changes in serum lipids were observed in tropifexor‐ vs placebo‐treated obese subjects. In conclusion, tropifexor was well tolerated, had a pharmacokinetic profile suitable for once‐daily dosing and showed dose‐dependent target engagement without altering plasma lipids in healthy volunteers.

Sodium fluorocitrate having inhibitory effect on fatty acid uptake ameliorates high fat diet-induced non-alcoholic fatty liver disease in C57BL/6J mice

Non-alcoholic fatty liver disease (NAFLD) is excessive fat build-up in the liver without alcohol consumption and includes hepatic inflammation and damage. Excessive influx of fatty acids to liver from circulation is thought to be a pathogenic cause for the development of NAFLD. Thus, inhibition of fatty acid intake into hepatocyte would be a maneuver for protection from high fat diet (HFD)-induced NAFLD. This study was initiated to determine whether sodium fluorocitrate (SFC) as a fatty acid uptake inhibitor could prevent palmitate-induced lipotoxicity in hepatocytes and protect the mice from HFD-induced NAFLD. SFC significantly inhibited the cellular uptake of palmitate in HepG2 hepatocytes, and thus prevented palmitate-induced fat accumulation and death in these cells. Single treatment with SFC reduced fasting-induced hepatic steatosis in C57BL/6J mice. Concurrent treatment with SFC for 15 weeks in HFD-fed C57BL/6J mice prevented HFD-induced fat accumulation and stress/inflammatory signal activation in the liver. SFC restored HFD-induced increased levels of serum alanine aminotransferase and aspartate aminotransferases as hepatic injury markers in these mice. SFC treatment also improved HFD-induced hepatic insulin resistance, and thus ameliorated HFD-induced hyperglycemia. In conclusion, inhibition of fatty acid mobilization into liver through SFC treatment can be a strategy to protect from HFD-induced NAFLD.

Evaluation of the effectiveness of eight screening tools in detecting risk of malnutrition in cirrhotic patients: the KIRRHOS study

Malnutrition risk screening in cirrhotic patients is crucial, as poor nutritional status negatively affects disease prognosis and survival. Given that a variety of malnutrition screening tools is usually used in routine clinical practice, the effectiveness of eight screening tools in detecting malnutrition risk in cirrhotic patients was sought. A total of 170 patients (57·1 % male, 59·4 (sd 10·5) years, 50·6 % decompensated ones) with cirrhosis of various aetiologies were enrolled. Nutritional screening was performed using the Malnutrition Universal Screening Tool, Nutritional Risk Index, Malnutrition Screening Tool, Nutritional Risk Screening (NRS-2002), Birmingham Nutritional Risk Score, Short Nutritional Assessment Questionnaire, Royal Free Hospital Nutritional Prioritizing Tool (RFH-NPT) and Liver Disease Undernutrition Screening Tool (LDUST). Malnutrition diagnosis was defined using the Subjective Global Assessment (SGA). Data on 1-year survival were available for 145 patients. The prevalence of malnutrition risk varied according to the screening tools used, with a range of 13·5–54·1 %. RFH-NPT and LDUST were the most accurate in detecting malnutrition (AUC = 0·885 and 0·892, respectively) with a high sensitivity (97·4 and 94·9 %, respectively) and fair specificity (73·3 and 58 %, respectively). Malnutrition according to SGA was an independent prognostic factor of within 1-year mortality (relative risk was 2·17 (95 % CI 1·0, 4·7), P = 0·049) after adjustment for sex, age, disease aetiology and Model for End-stage Liver Disease score, whereas nutrition risk according to RFH-NPT, LDUST and NRS-2002 showed no association. RFH-NPT and LDUST were the only screening tools that proved to be accurate in detecting malnutrition in cirrhotic patients.

Human Umbilical Cord-Derived Mesenchymal Stem Cell Therapy Ameliorates Nonalcoholic Fatty Liver Disease in Obese Type 2 Diabetic Mice

Nonalcoholic fatty liver disease (NAFLD) is increasingly common among patients with type 2 diabetes mellitus (T2DM). The two conditions can act synergistically to produce adverse outcomes. However, the therapeutic options for patients with NAFLD and T2DM are currently limited. Human umbilical cord-derived mesenchymal stem cells (UC-MSCs) have shown therapeutic potential for diabetes and hepatic disorders such as liver cirrhosis and fulminant hepatic failure. The present study is aimed at investigating the effect of human UC-MSCs on a mouse model of NAFLD and T2DM, characterized by obesity-induced hyperglycaemia, dyslipidaemia, hepatic steatosis, and liver dysfunction. Thirty-week-old male C57BL/6 db/db mice were infused with human UC-MSCs or phosphate-buffered saline (PBS) via the tail vein once a week for six weeks. Age-matched male C57BL/6 wild-type db/+ mice were used as controls. Body weight and random blood glucose were measured every week. One week after the sixth infusion, intraperitoneal glucose tolerance tests and insulin tolerance tests were performed and the blood and liver were harvested for biochemical and histopathological examinations. Quantitative real-time reverse transcriptase polymerase chain reaction (qRT-PCR), immunofluorescence staining, and western blot were performed to monitor the expression of the lipid metabolism- and regulatory pathway-related genes. UC-MSC infusions significantly ameliorated hyperglycaemia, attenuated the elevation of hepatic transaminases, and decreased lipid contents, including triglyceride, total cholesterol, and low-density lipoprotein cholesterol. Moreover, histological lesions in the liver diminished markedly, as evidenced by reduced lipid accumulation and attenuated hepatic steatosis. Mechanistically, UC-MSCs were found to regulate lipid metabolism by increasing the expression of fatty acid oxidation-related genes and inhibiting the expression of lipogenesis-related genes, which were associated with the upregulation of the HNF4α-CES2 pathway. Our results demonstrate that human UC-MSCs can ameliorate NAFLD and reverse metabolic syndrome in db/db mice. Thus, UC-MSCs may serve as a novel therapeutic agent for T2DM patients with NAFLD.

Oral ethinylestradiol–levonorgestrel normalizes fructose-induced hepatic lipid accumulation and glycogen depletion in female rats

The present study investigated the effects of oral ethinylestradiol–levonorgestrel (EEL) on hepatic lipid and glycogen contents during high fructose (HF) intake, and determined whether pyruvate dehydrogenase kinase-4 (PDK-4) and glucose-6-phosphate dehydrogenase (G6PD) activity were involved in HF and (or) EEL-induced hepatic dysmetabolism. Female Wistar rats weighing 140–160 g were divided into groups. The control, EEL, HF, and EEL+HF groups received water (vehicle, p.o.), 1.0 μg ethinylestradiol plus 5.0 μg levonorgestrel (p.o.), fructose (10% w/v), and EEL plus HF, respectively, on a daily basis for 8 weeks. Results revealed that treatment with EEL or HF led to insulin resistance, hyperinsulinemia, increased hepatic uric acid production and triglyceride content, reduced glycogen content, and reduced production of plasma or hepatic glutathione- and G6PD-dependent antioxidants. HF but not EEL also increased fasting glucose and hepatic PDK-4. Nonetheless, these alterations were attenuated by EEL in HF-treated rats. Our results demonstrate that hepatic lipid accumulation and glycogen depletion induced by HF is accompanied by increased PDK-4 and defective G6PD activity. The findings also suggest that EEL would attenuate hepatic lipid accumulation and glycogen depletion by suppression of PDK-4 and enhancement of a G6PD-dependent antioxidant barrier.

Extracellular Matrix Remodeling of Adipose Tissue in Obesity and Metabolic Diseases

The extracellular matrix (ECM) is a network of different proteins and proteoglycans that controls differentiation, migration, repair, survival, and development, and it seems that its remodeling is required for healthy adipose tissue expansion. Obesity drives an excessive lipid accumulation in adipocytes, which provokes immune cells infiltration, fibrosis (an excess of deposition of ECM components such as collagens, elastin, and fibronectin) and inflammation, considered a consequence of local hypoxia, and ultimately insulin resistance. To understand the mechanism of this process is a challenge to treat the metabolic diseases. This review is focused at identifying the putative role of ECM in adipose tissue, describing its structure and components, its main tissue receptors, and how it is affected in obesity, and subsequently the importance of an appropriate ECM remodeling in adipose tissue expansion to prevent metabolic diseases.

Obesity Paradox in Chronic Liver Diseases: Product of Bias or a Real Thing?

In recent years, evidence supporting the theory of obesity paradox has increased, showing that obese/overweight people with prevalent chronic diseases experience lower mortality compared with patients of normal weight. So far, evidence is most comprehensive in cardiovascular and chronic renal diseases; however, published studies are prone to many biases, enabling us to reach a definite conclusion. Available data in chronic liver disease is scarce and ambiguous. Obesity is traditionally associated with nonalcoholic fatty liver disease and steatosis in viral hepatitis and as such one would not expect the obesity paradox to be a real possibility in liver disease. Yet, there seem to be new data indicating the opposite - the obesity paradox exists in severe and end-stage liver cirrhosis, which could be attributed to a better lean mass in patients with higher body mass index, meaning that sarcopenia, as one of the most important prognostic factors of survival, is less likely to be present. Nonetheless, the problem of various methodological problems addressing the association between body weight and mortality, which is present both in liver disease and other chronic diseases, are preventing us from attaining an unanimous conclusion. Still, we should be aware that the obesity paradox might be true, especially in severe and end-stage illness. This suggests focusing our efforts toward preserving or building up fat-free mass and decreasing inflammatory activity responsible for catabolism and sarcopenia, and implying that the underlaying cause should be treated.

Berberine inhibits adipocyte differentiation, proliferation and adiposity through down-regulating galectin-3

This study is designed to investigate the effects of berberine (BBR) on galectin-3 (Gal-3) and the relationships to its suppressive activities on adipocyte differentiation, proliferation and adiposity. Our results showed that BBR greatly suppressed the differentiation and proliferation of mouse primary preadipocytes isolated from epididymal white adipose tissue (eWAT), during which the expression level of Gal-3 was down-regulated significantly. Overexpression of Gal-3 totally abolished the suppressive activities of BBR on Gal-3 expression, preadipocyte differentiation and proliferation. BBR reduced Gal-3 promoter activity, destabilized its mRNA and inhibited firefly luciferase activity of a recombinant plasmid containing the Gal-3 3′ untranslated region (UTR). Furthermore, BBR up-regulated microRNA (miRNA) let-7d expression and the suppressive activity on Gal-3 3′UTR was abolished by point mutation on the let-7d binding site. In mice fed a high-fat diet (HFD), BBR up-regulated let-7d and down-regulated Gal-3 expression in eWAT; it also suppressed adipocyte differentiation and proliferation and reduced adiposity greatly. In summary, our study proves that BBR inhibits the differentiation and proliferation of adipocytes through down-regulating Gal-3, which is closely associated with its anti-obesity effect. Our results may support the future clinical application of BBR for the treatment of obesity or related diseases.

Preparation and Evaluation of Functional Foods for Prevention of Non-alcoholic Fatty Liver Disease

BACKGROUND AND OBJECTIVE

Non-alcoholic fatty liver disease (NAFLD) is a public health problem presenting one of the most important common forms of liver diseases worldwide. This study was carried out to investigate the protective effect of two functional foods in form of bread containing purslane seeds meal and garden cress seeds against NAFLD.

MATERIALS AND METHODS

High fat and high cholesterol diet were used for induction of NAFLD in rats for 6 weeks. Plasma lipid profile (total cholesterol, triglycerides, high density lipoprotein-cholesterol and low-density lipoprotein-cholesterol, hepatic lipid profile (total fat, cholesterol, triglycerides), malondialdehyde (MDA), as well as liver (AST, ALT, total and direct bilirubin) and kidney (creatinine and urea) functions were assessed. Histological examination of liver tissue was carried out.

RESULTS

Results revealed that significant elevation in plasma and liver lipid profiles, MDA, liver enzymes (AST and ALT), bilirubin (total and direct) and kidney function (creatinine and urea) were observed in NAFLD control compared to normal control. Feeding rats on diet containing functional food I and II (purslane and garden cress bread, respectively) showed significant improvement in all the studied parameters with remarkable effect regards to functional food I (purslane bread).

CONCLUSION

Purslane bread and garden cress bread as functional foods prepared in the present study prevent weight gain, improve plasma lipid profile and prevent hepatic lipid accumulation effectively in NAFLD model in rats. Also decreased lipid peroxidation, improve liver and kidney functions and possess hypoglycemic effect. Purslane bread was superior in the prevention of hepatic lipid accumulation.

Loss of hepatic PPARα promotes inflammation and serum hyperlipidemia in diet-induced obesity

Agonists for PPARα are used clinically to reduce triglycerides and improve high-density lipoprotein (HDL) cholesterol levels in patients with hyperlipidemia. Whether the mechanism of PPARα activation to lower serum lipids occurs in the liver or other tissues is unknown. To determine the function of hepatic PPARα on lipid profiles in diet-induced obese mice, we placed hepatocyte-specific peroxisome proliferator-activated receptor-α (PPARα) knockout (Ppara^HepKO) and wild-type (Ppara^fl/fl) mice on high-fat diet (HFD) or normal fat diet (NFD) for 12 wk. There was no significant difference in weight gain, percent body fat mass, or percent body lean mass between the groups of mice in response to HFD or NFD. Interestingly, the Ppara^HepKO mice on HFD had worsened hepatic inflammation and a significant shift in the proinflammatory M1 macrophage population. These changes were associated with higher hepatic fat mass and decreased hepatic lean mass in the Pparα^HepKO on HFD but not in NFD as measured by Oil Red O and noninvasive EchoMRI analysis (31.1 ± 2.8 vs. 20.2 ± 1.5, 66.6 ± 2.5 vs. 76.4 ± 1.5%, P < 0.05). We did find that this was related to significantly reduced peroxisomal gene function and lower plasma β-hydroxybutyrate in the Ppara^HepKO on HFD, indicative of reduced metabolism of fats in the liver. Together, these provoked higher plasma triglyceride and apolipoprotein B100 levels in the Ppara^HepKO mice compared with Ppara^fl/fl on HFD. These data indicate that hepatic PPARα functions to control inflammation and liver triglyceride accumulation that prevent hyperlipidemia.

Smoking results in accumulation of ectopic fat in the liver

OBJECTIVE

An association between smoking and nonalcoholic fatty liver disease has been reported. However, objective quantification of intrahepatic fat via magnetic resonance spectroscopy (MRS) in relation to smoking has rarely been performed in previous studies. Moreover, the possible pathways via which smoking could induce ectopic fat accumulation have not yet been addressed. The current study aimed to examine the association between smoking status and intrahepatic fat quantity and explore the possible mediating effects of triglycerides (TG) and adiponectin.

SUBJECTS AND METHODS

Magnetic resonance imager (MRI) spectra were analyzed to quantify intrahepatic fat in 45 men who were on average 62.3 years of age. Smoking status and alcohol intake were self-reported. Accelerometers were used to record daily total physical activity. Fasting blood TG and adiponectin levels were measured enzymatically. Differences in mean intrahepatic fat values according to smoking status were assessed using analysis of covariance.

RESULTS

A stepwise increase in mean intrahepatic fat was observed between never, former, and current smokers, respectively, independent of age, physical activity, alcohol intake, and body mass index (BMI) (P=0.005). Adjustment for TG and adiponectin significantly attenuated this association (P=0.074).

CONCLUSION

Current smoking was significantly associated with increased intrahepatic fat, which may be a result of adipocyte dysfunction, manifested as high circulating TG concentrations and low adiponectin levels.

Dietary patterns in relation to hepatic fibrosis among patients with nonalcoholic fatty liver disease

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is a multifactorial disorder that can progress to fibrosis. Several dietary patterns have been associated with histological features of NAFLD. However, little is known about the association between dietary patterns and hepatic fibrosis.

PURPOSE

The current study aimed at identifying the relationship between major dietary patterns and hepatic fibrosis among patients with NAFLD.

SUBJECTS AND METHODS

This cross-sectional study included 170 eligible subjects with NAFLD. Diet was evaluated using three 3-day dietary records during a 1-month period. Hepatic fibrosis was diagnosed using Fibroscan. Western, Iranian, and healthy dietary patterns were extracted using factor analysis.

RESULTS

After adjustment for other risk factors, adherence to a Western dietary pattern was associated with the higher odds of fibrosis (OR: 4.21; 95% CI: 1.63-8.31), whereas adherence to a healthy dietary pattern was associated with the lower odds of fibrosis (OR: 0.26; 95% CI: 0.10-0.49). Among main food groups, high intake of red meat, hydrogenated fats, and soft drinks was associated with the higher risk of fibrosis, whereas tea and coffee consumption had a protective role in hepatic fibrosis independent of other risk factors.

CONCLUSION

The adherence to a healthy dietary pattern characterized by high intake of low-fat dairies, white meat, nuts, vegetables, fruits, and vegetable oils combined with coffee and tea consumption might be helpful in the nutritional strategies against hepatic fibrosis.