Expression of inflammation-related genes is altered in gastric tissue of patients with advanced stages of NAFLD. Mediators Inflamm. 2013;2013:684237. [PMID: 23661906 PMCID: PMC3626032 DOI: 10.1155/2013/684237]

Protective effect of lyophilized sapodilla (Manilkara zapota) fruit extract against CCl4-induced liver damage in rats

The tropical fruit sapodilla (Manilkara zapota syn. Achras zapota) is a rich source of nutrients, minerals and a myriad of bioactive phytochemicals such as flavonoids and catechins. Pharmacologically, sapodilla has been shown to exhibit anti-bacterial, anti-parasitic, anti-fungal, antiglycative, hypocholesterolemic and anti-cancer effects. However, its influence on hepatic tissue and serum lipids remains obscure. To address this, we used an in vivo model of liver damage to elucidate the effect of lyophilized sapodilla extract (LSE) treatment in carbon tetra chloride (CCl₄) intoxicated rats. Exposure of CCl₄ resulted in elevation of serum biomarkers of liver damage (aspartate transaminase, alanine aminotransferase, γ-glutamyl transferase and alkaline phosphatase), bilirubin and dysregulation of serum lipid profile (cholesterol and triglycerides). These effects were significantly and dose-dependently reversed by LSE treatment (250 and 500 mg/kg). Administration of LSE also reduced the structural damage caused by CCl₄ in the liver. Furthermore, determination of oxidative stress parameters (malondialdehyde and non-protein sulfhydryls) revealed that LSE treatment mitigated CCl₄-triggered modulation of both molecules. LSE also showed a strong antioxidant activity in 2,2-diphenyl-1-picrylhydrazyl (DPPH) and β-carotene-linoleic acid assays. In conclusion, the present study discloses the hepatoprotective and lipid-lowering effects of lyophilized sapodilla extract against CCl₄-induced liver damage, an effect, at least in part, mediated by its antioxidant activity.

The Stomach as an Endocrine Organ: Expression of Key Modulatory Genes and Their Contribution to Obesity and Non-alcoholic Fatty Liver Disease (NAFLD)

PURPOSE OF REVIEW

Obesity is currently seen in epidemic proportions globally and is one of the largest contributors to the development of NAFLD. The spectrum of NAFLD, particularly the progressive forms of NASH, is likely to become the leading cause of liver disease in the next decade.

RECENT FINDINGS

Soluble molecules, encoded by the stomach tissue, have been shown to have pleiotropic effects in both central and peripheral systems involved in energy homeostasis and obesity regulation. As such, the stomach is one of the important players in the complex, multi-system deregulation leading to obesity and NAFLD. The understanding of the stomach tissue as an active endocrine organ that contributes to the signaling milieu leading to the development of obesity and NAFLD is crucial.

Impact of nonalcoholic fatty liver disease on multiple human body systems

Non-alcoholic fatty liver disease (NAFLD) is a clinicpathologic syndrome characterized by hepatocellular steatosis and fat deposition in individuals in the absence of significant alcohol intake and other specific factors that can impair liver function. According to epidemiological investigations, NAFLD has become one of the most common liver diseases in China. More and more studies show that NAFLD can influence many human body systems. This paper reviews the possible effect of NAFLD on the cardiovascular system, digestive system, respiratory system, urinary system, metabolic system and nervous system.

Genomics of human fatty liver disease reveal mechanistically linked lipid droplet-associated gene regulations in bland steatosis and nonalcoholic steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) is a common disorder hallmarked by excessive lipid deposits. Based on our recent research on lipid droplet (LD) formation in hepatocytes, we investigated LD-associated gene regulations in NAFLD of different grades, that is, steatosis vs steatohepatitis by comparing liver biopsies from healthy controls (N = 13) and NAFLD patients (N = 102). On average, more than 700 differentially expressed genes (DEGs) were identified of which 146 are mechanistically linked to LD formation. We identified 51 LD-associated DEGs frequently regulated in patient samples (range ≥5 to ≤102) with the liver-receptor homolog-1(NR5A2), that is, a key regulator of cholesterol metabolism being commonly repressed among 100 patients examined. With bland steatosis, notable regulations involved hypoxia-inducible lipid droplet-associated-protein and diacylglycerol-O-acyltransferase-2 renowned for their role in LD-growth. Conversely, nonalcoholic steatohepatitis-associated DEGs coded for epidermal growth factor receptor and TLR4 signaling with decreased expression of the GTPase Rab5 and the lipid phosphohydrolase PPAP2B thus highlighting adaptive responses to inflammation, LDL-mediated endocytosis and lipogenesis, respectively. Studies with steatotic primary human hepatocyte cultures demonstrated induction of LD-associated PLIN2, CIDEC, DNAAF1, whereas repressed expression of CPT1A, ANGPTL4, and PKLR informed on burdened mitochondrial metabolism. Equally, repressed expression of the B-lymphocyte chemoattractant CXCL13 and STAT4 as well as induced FGF21 evidenced amelioration of steatosis-related inflammation. In-vitro/in-vivo patient sample comparisons confirmed C-reactive protein, SOCS3, NR5A2, and SOD2 as commonly regulated. Lastly, STRING network analysis highlighted potential "druggable" targets with PLIN2, CIDEC, and hypoxia-inducible lipid droplet-associated-protein being confirmed by immunofluorescence microscopy. In conclusion, steatosis and steatohepatitis specific gene regulations informed on the pathogenesis of NAFLD to broaden the perspective of targeted therapies.

CXCL10 plays a key role as an inflammatory mediator and a non-invasive biomarker of non-alcoholic steatohepatitis

BACKGROUND & AIMS

Perpetuate liver inflammation is crucial in the pathogenesis of non-alcoholic steatohepatitis (NASH). Expression of CXCL10, a pro-inflammatory cytokine, correlates positively with obesity and type 2 diabetes. Whether CXCL10 plays a role in NASH was unknown. We aimed to investigate the functional and clinical impact of CXCL10 in NASH.

METHODS

Cxcl10 gene-deleted (Cxcl10(-/-)) and C57BL/6 wild type (WT) mice were fed a methionine- and choline-deficient (MCD) diet for 4 or 8 weeks. In other experiments, we injected neutralizing anti-CXCL10 mAb into MCD-fed WT mice. Human serum was obtained from 147 patients with biopsy-proven non-alcoholic fatty liver disease and 73 control subjects.

RESULTS

WT mice, fed the MCD diet, developed steatohepatitis with higher hepatic CXCL10 expression. Cxcl10(-/-) mice were refractory to MCD-induced steatohepatitis. We further revealed that CXCL10 was associated with the induction of important pro-inflammatory cytokines (TNF-α, IL-1β, and MCP-1) and activation of the NF-κB pathway. CXCL10 was linked to steatosis through upregulation of the lipogenic factors SREBP-1c and LXR, and also to oxidative stress (upregulation of CYP2E1 and C/EBPβ). Blockade of CXCL10 protected against hepatocyte injury in vitro and against steatohepatitis development in mice. We further investigated the clinical impact of CXCL10 and found circulating and hepatic CXCL10 levels were significantly higher in human NASH. Importantly, the circulating CXCL10 level was correlated with the degree of lobular inflammation and was an independent risk factor for NASH patients.

CONCLUSIONS

We demonstrate for the first time that CXCL10 plays a pivotal role in the pathogenesis of experimental steatohepatitis. CXCL10 maybe a potential non-invasive biomarker for NASH patients.

Expression of energy metabolism related genes in the gastric tissue of obese individuals with non-alcoholic fatty liver disease

Background

Stomach is an integral part of the energy balance regulating circuit. Studies exploring the effects of cross-system changes in the energy homeostasis in stomach tissue are scarce. The proximity of the stomach to liver - the most common secondary target affected by obesity – suggests that these two organs are exposed to each other’s local secretion. Therefore, we aimed at expression profiling of energy metabolism associated genes in the gastric tissue of obese non-alcoholic fatty liver disease (NAFLD) patients.

Methods

A total of 24 patients with histologically-proven NAFLD were included. In the gastric tissue, gene expression profiling of 84 energy metabolism associated genes was carried out.

Results

The accumulation of the fat in the liver parenchyma is accompanied by downregulation of genes encoding for carboxypeptidase E (CPE) and Interleukin 1B (IL1B) in the gastric mucosa of same patient. In patients with high grade hepatic steatosis, Interleukin 1 beta encoding gene with anorexigenic function, IL1B was downregulated. The levels expression of 21 genes, including ADRA2B, CNR1 and LEP were significantly altered in the gastric tissue of NAFLD patients with hepatic inflammation. There were also indications of an increase in the opioid signaling within gastric mucosa that may results in a shift to proinflammatory environment within this organ and contribute to systemic inflammation and the pathogenic processes in hepatic parenchyma.

Conclusions

We have shown differential expression of energy metabolism associated genes in the gastric tissue of obese NAFLD patients. Importantly, these gene expression profiles are associated with changes in the hepatic parenchyma as reflected in increased scores for hepatic steatosis, inflammation, fibrosis and NASH. This study suggests the complex interplay of multiple organs in the pathogenesis of obesity-related complications such as NAFLD and provides further evidence supporting an important role for gastric tissue in promoting obesity-related complications.