Different Stages Of Nonalcoholic Fatty Liver Disease Research Articles

Experimental study on role of cannabinoid receptor 1 in non-alcoholic fatty liver disease among rats

Objective To observe the expression of endogenous cannabinoid receptor l (CB1) in rats with non-alcoholic fatty liver disease (NAFLD) and to preliminarily investigate the role of CB1 receptors in the pathogenesis of NAFLD. Methods Forty-eight male SD rats were randomly divided into three groups: control group (receiving normal feed), model group (receiving high-sugar and high-fat feed), and rimonabant group (receiving high-sugar and high-fat feed and rimonabant). At the end of the 4th or 8th week of experiment, 8 of each group were sacrificed. The body weight was measured, and the liver index was calculated. The serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), triglyceride (TG), and total cholesterol (TC) were determined. The serum levels of leptin and tumor necrosis factor (TNF)α were determined by ELISA. The liver tissue was treated by HE staining, and the pathological changes were observed. Immunohistochemical staining was used to evaluate the CB1 receptor expression in liver tissues in different stages of NAFLD. One-way analysis of variance and t-test were used for within-group and between-group comparisons. Pearson′s linear-correlation analysis was used for evaluating the correlation between indices. Results The model group had significantly higher serum levels of ALT, AST, TC, TG, leptin, and TNF-α than the control group and rimonabant group (P＜0.05). The model group showed simple fatty degeneration of the liver after 4 weeks and diffuse fatty degeneration of the liver with inflammatory cell infiltration after 8 weeks, while the rimonabant group had less severe liver lesions at the same time. CB1 receptor expression was not detected in the control group, but was detected in the model group and rimonabant group, according to the immunohistochemical staining, and the model group had a significantly higher integral optical density than the rimonabant group (P＜0.05). Conclusion The expression of CB1 receptors is enhanced in patients with NAFLD, and it may act together with TNF-α and leptin to promote the progression of NAFLD.

Molecular Interactions between NAFLD and Xenobiotic Metabolism

Non-alcoholic fatty liver disease (NAFLD), the hepatic manifestation of the metabolic syndrome, is a complex multifactorial disease characterized by metabolic deregulations that include accumulation of lipids in the liver, lipotoxicity, and insulin resistance. The progression of NAFLD to non-alcoholic steatohepatitis and cirrhosis, and ultimately to carcinomas, is governed by interplay of pro-inflammatory pathways, oxidative stress, as well as fibrogenic and apoptotic cues. As the liver is the major organ of biotransformation, deregulations in hepatic signaling pathways have effects on both, xenobiotic and endobiotic metabolism. Several major nuclear receptors involved in the transcription and regulation of phase I and II drug metabolizing enzymes and transporters also have endobiotic ligands including several lipids. Hence, hepatic lipid accumulation in steatosis and NAFLD, which leads to deregulated activation patterns of nuclear receptors, may result in altered drug metabolism capacity in NAFLD patients. On the other hand, genetic and association studies have indicated that a malfunction in drug metabolism can affect the prevalence and severity of NAFLD. This review focuses on the complex interplay between NAFLD pathogenesis and drug metabolism. A better understanding of these relationships is a prerequisite for developing improved drug dosing algorithms for the pharmacotherapy of patients with different stages of NAFLD.

Cardiometabolic risk factors in different clinicomorphological stages of non-alcoholic fatty liver disease in patients with abdominal obesity

The aim of the study was to compare clinical, laboratory and morphological parameters in patients with abdominal obesity and non-alcoholic fatty liver disease (NAFLD), and assessing the relationship between the degree of severity, stage NAFLD and cardiometabolic risk factors for type 2 diabetes mellitus and cardiovascular disease. The present study examined the content of adiponectin and rates of glucose and lipid metabolism in obese patients at different stages of NAFLD. According to the study, morphologically NAFLD was confirmed in 95.2% of patients. NAFLD was associated with various cardiometabolic disorders (dyslipidemia, disorders of glucose metabolism and insulin resistance), growing in frequency and severity with the progression NAFLD; and low levels of adiponectin decreasing with a deterioration NAFLD.

Ursodeoxycholyl lysophosphatidylethanolamide improves steatosis and inflammation in murine models of nonalcoholic fatty liver disease

Hepatic fat accumulation and changes in lipid composition are hallmarks of nonalcoholic fatty liver disease (NAFLD). As an experimental approach for treatment of NAFLD, we synthesized the bile acid-phospholipid conjugate ursodeoxycholyl lysophosphatidylethanolamide (UDCA-LPE). Previous work demonstrated profound hepatoprotective properties of the conjugate in vitro and in vivo. Here we investigated the effects of UDCA-LPE in two nutritional mouse models of NAFLD. C57BL/6 mice were fed a high-fat diet (HFD) for 28 weeks, resulting in steatosis with hyperlipidemia. In a second model, mice received a methionin-choline-deficient (MCD) diet for up to 11 weeks, which induced advanced nonalcoholic steatohepatitis (NASH). Establishment of liver injury was followed by intraperitoneal injections of 30 mg/kg UDCA-LPE three times a week for different time periods. UDCA-LPE ameliorated both HFD- and MCD-induced increases in alanine aminotransferase (ALT) values near to normalization. As for metabolic parameters, UDCA-LPE reduced elevated serum triglyceride and cholesterol values in HFD mice. Liver histology showed improvement of steatosis in HFD and MCD mice concomitant with reductions in hepatic triglyceride and cholesterol levels. Additionally, the conjugate lowered serum caspase-8 activity in both models and decreased lipid hydroperoxides in MCD mice. Abundance of proinflammatory lysophosphatidylcholine (LPC), which was detectable in both HFD and MCD mice, was reduced by UDCA-LPE. Quantitative reverse transcriptase-polymerase chain reaction qRT-PCR of liver specimens revealed that UDCA-LPE strongly down-regulated inflammatory genes and modified the expression of genes involved in lipid metabolism. The current study demonstrates that UDCA-LPE improves hepatic injury at different stages of NAFLD. By concurrently lowering hepatic lipid overloading as well as susceptibility of hepatocytes toward inflammatory stimuli, the conjugate may be able to ameliorate disease progression. Thus, UDCA-LPE represents a promising compound suitable for the treatment of NAFLD.

A Proton Nuclear Magnetic Resonance Metabonomics Approach for Biomarker Discovery in Nonalcoholic Fatty Liver Disease

This study was undertaken to discover novel biomarkers for the noninvasive early diagnosis of nonalcoholic fatty liver disease (NAFLD). A methionine and choline deficient (MCD) diet was used to represent different stages of NAFLD in male C57BL/6 mice. (1)H NMR spectroscopy and principal components analysis (PCA) were used to investigate the time-related biochemical changes in mice sera induced by the MCD diet. Many serum metabolites' concentrations changed between control and MCD-fed mice. Hierarchical cluster analysis (HCA) and artificial neural networks (ANNs) were used to select the least number of metabolites to be used for the noninvasive diagnosis of various stages of NAFLD; four potential biomarkers, serum glucose, lactate, glutamate/glutamine, and taurine were selected. To verify the diagnostic accuracy of these selected metabolites, their serum concentrations were measured in healthy controls (n = 28), NAFLD patients with steatosis (n = 15), steatosis patients with necro-inflammatory disease (n = 11), and NASH patients (n = 6). On the basis of results from MCD-fed mice model, clinical tests, and previous reports, we propose using the levels of the four metabolites for diagnosing NAFLD at various stages. Furthermore, the probability of developing NAFLD at a particular stage was assessed by multinomial logistic regression (MLR) based on the clinical results of the four serum metabolites.

Lipotoxicity and steatohepatitis in an overfed mouse model for non-alcoholic fatty liver disease

The major risk factors for non-alcoholic fatty liver disease (NAFLD) are obesity, insulin resistance and dyslipidemia. The cause for progression from the steatosis stage to the inflammatory condition (non-alcoholic steatohepatitis (NASH)) remains elusive at present. Aim of this study was to test whether the different stages of NAFLD as well as the associated metabolic abnormalities can be recreated in time in an overfed mouse model and study the mechanisms underlying the transition from steatosis to NASH.Male C57Bl/6J mice were subjected to continuous intragastric overfeeding with a high-fat liquid diet (HFLD) for different time periods. Mice fed a solid high-fat diet (HFD) ad libitum served as controls. Liver histology and metabolic characteristics of liver, white adipose tisue (WAT) and plasma were studied.Both HFD-fed and HFLD-overfed mice initially developed liver steatosis, but only the latter progressed in time to NASH. NASH coincided with obesity, hyperinsulinemia, loss of liver glycogen and hepatic endoplasmatic reticulum stress. Peroxisome proliferator-activated receptor γ (Pparγ), fibroblast growth factor 21 (Fgf21), fatty acid binding protein (Fabp) and fatty acid translocase (CD36) were induced exclusively in the livers of the HFLD-overfed mice. Inflammation, reduced adiponectin expression and altered expression of genes that influence adipogenic capacity were only observed in WAT of HFLD-overfed mice.In conclusion: this dietary mouse model displays the different stages and the metabolic settings often found in human NAFLD. Lipotoxicity due to compromised adipose tissue function is likely associated with the progression to NASH, but whether this is cause or consequence remains to be established.

Experimental non-alcoholic fatty liver disease results in decreased hepatic uptake transporter expression and function in rats

Non-alcoholic fatty liver disease (NAFLD) encompasses a spectrum of diagnoses ranging from simple fatty liver (SFL), to non-alcoholic steatohepatitis (NASH). This study aimed to determine the effect of moderate and severe NAFLD on hepatic transporter expression and function in vivo. Rats were fed a high-fat diet (SFL model) or a methionine-choline-deficient diet (NASH model) for eight weeks. Hepatic uptake transporter function was determined by bromosulfophthalein (BSP) disposition. Transporter expression was determined by branched DNA signal amplification assay and western blotting; inflammation was identified by immunostaining of liver slices for interleukin 1 beta (IL-1β). MC− rats showed significant retention of BSP in the plasma when compared to control rats. Hepatic NTCP, OATP1a1, 1a4, 1b2 and 2b1; and OAT 2 and 3 mRNA levels were significantly decreased in high-fat and MC− diet rats when compared to control. Protein expression of OATP1a1 was significantly decreased in high-fat animals, while OATP1a1 and OATP1b2 expressions were significantly lower in MC− rats when compared to control. Liver tissue from high-fat and MC− rats stained positive for IL-1β, a pro-inflammatory cytokine known to decrease expression of NTCP, OATP and OAT transporters, suggesting a plausible mechanism for the observed transporter alterations. These data suggest that different stages of NAFLD result in altered hepatic uptake transporter expression that can lead to a functional impairment of xenobiotic uptake from the blood. Furthermore, NAFLD may alter the plasma retention time of clinically relevant drugs that are reliant on these transporters and may increase the potential drug toxicity.