Pharmacological evaluation of pioglitazone and candesartan cilexetil in a novel mouse model of non-alcoholic steatohepatitis, modified choline-deficient, amino acid-defined diet fed low-density lipoprotein receptor knockout mice

Validation of a diet-induced Macaca fascicularis model of non-alcoholic steatohepatitis with dietary and pioglitazone interventions

AIM

To develop an obese, insulin-resistant cynomolgus monkey model of non-alcoholic steatohepatitis (NASH) with fibrosis with a high fat/high cholesterol (HFHC) diet (with or without high fructose) and test its responsiveness to caloric restriction or pioglitazone.

METHODS

First, two groups of monkeys (n = 24/group) with histologically proven NASH and fibrosis were fed the HFHC diet for 17 weeks. The treatment group was subjected to a 40% caloric restriction (CR) and had their diet switched from the HFHC diet to a chow diet (DSCR). Paired liver biopsies were taken before and 17 weeks after DSCR. Subsets of monkeys (nine/group) had whole liver fat content assessed by MRI. Next, two groups of monkeys with histologically proven NASH and fibrosis were treated with vehicle (n = 9) or pioglitazone (n = 20) over 24 weeks.

RESULTS

The HFHC and DSCR groups lost 0.9% and 11.4% of body weight, respectively. After 17 weeks, non-alcoholic fatty liver disease activity score (NAS) improvement was observed in 66.7% of the DSCR group versus 12.5% of the HFHC group (P < .001). Hepatic fat was reduced to 5.2% in the DSCR group versus 23.0% in the HFHC group (P = .0001). After 24 weeks, NAS improvement was seen in 30% of the pioglitazone group versus 0% of the vehicle group (P = .08).

CONCLUSIONS

Both weight loss induced by DSCR and treatment with pioglitazone improve the histological features of NASH in a diet-induced cynomolgus monkey model. This model provides a translational preclinical model for testing novel NASH therapies.

Polydatin inhibits ZEB1-invoked epithelial-mesenchymal transition in fructose-induced liver fibrosis

High fructose intake is a risk factor for liver fibrosis. Polydatin is a main constituent of the rhizome of Polygonum cuspidatum, which has been used in traditional Chinese medicine to treat liver fibrosis. However, the underlying mechanisms of fructose-driven liver fibrosis as well as the actions of polydatin are not fully understood. In this study, fructose was found to promote zinc finger E-box binding homeobox 1 (ZEB1) nuclear translocation, decrease microRNA-203 (miR-203) expression, increase survivin, activate transforming growth factor β1 (TGF-β1)/Smad signalling, down-regulate E-cadherin, and up-regulate fibroblast specific protein 1 (FSP1), vimentin, N-cadherin and collagen I (COL1A1) in rat livers and BRL-3A cells, in parallel with fructose-induced liver fibrosis. Furthermore, ZEB1 nuclear translocation-mediated miR-203 low-expression was found to target survivin to activate TGF-β1/Smad signalling, causing the EMT in fructose-exposed BRL-3A cells. Polydatin antagonized ZEB1 nuclear translocation to up-regulate miR-203, subsequently blocked survivin-activated TGF-β1/Smad signalling, which were consistent with its protection against fructose-induced EMT and liver fibrosis. These results suggest that ZEB1 nuclear translocation may play an essential role in fructose-induced EMT in liver fibrosis by targeting survivin to activate TGF-β1/Smad signalling. The suppression of ZEB1 nuclear translocation by polydatin may be a novel strategy for attenuating the EMT in liver fibrosis associated with high fructose diet.

Pioglitazone ameliorates hepatic damage in irradiated rats via regulating anti-inflammatory and antifibrogenic signalling pathways

Hepatic irradiation during radiotherapy is associated with liver damage. The current study was designed to investigate the possible modulatory effects of pioglitazone against γ irradiation-induced hepatic damage in rats. Animals were exposed to a single dose of 6 Gy and received pioglitazone (10 mg/kg/day) orally for 4 weeks starting on the same day of irradiation. Results showed that irradiation increased aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities as well as serum triglyceride (TG) and total cholesterol (TC) levels. Furthermore, it elevated inflammatory mediators; tumour necrosis factor alpha (TNF-α), interleukin-6 (IL-6); nuclear factor kappa B (NF-κB) and inducible nitric oxide synthase (iNOS) in hepatic tissues. Moreover, it increased levels of serum fibrotic markers; hyaluronic acid (HA), laminin (LN), and type III procollagen (PCIII). Additionally, hepatic fibrotic markers; transforming growth factor-β1 (TGF-β1) and hydroxyproline (HP) levels were elevated. Histological analysis of H&E and MT staining of liver sections exhibited cellular infiltration and fibrous deposition in irradiated rats. It was observed that pioglitazone modulated the described deviations. In conclusion, pioglitazone could serve as a promising therapeutic tool for attenuating radiation-induced liver injury in patients with radiotherapy which might be attributed to its anti-inflammatory and antifibrotic activities.

Analogy between non-alcoholic steatohepatitis (NASH) and hypertension: a stepwise patient-tailored approach for NASH treatment

Non-alcoholic steatohepatitis (NASH) is a common liver disorder worldwide. Although there has been improvement in our understanding of the natural history and pathogenesis of the disease, there is still no approved therapy for NASH. NASH shares many similarities with primary hypertension, in that both are extremely common disorders that can easily lead to serious complications if left untreated. Both conditions are viewed as "silent killers", because the disease can progress over a period of time prior to the occurrence of potentially deadly outcomes. While attempts to find the "miracle pill" for NASH are unrealistic, we can make an analogy with the "stepwise combination" approach developed over the last few decades for the treatment of hypertension. In the present review, we summarize some of the similarities in the concepts that underlie NASH and hypertension. The development of a stepwise patient-tailored method for the treatment of NASH is presented.

The Combination of Blueberry Juice and Probiotics Ameliorate Non-Alcoholic Steatohepatitis (NASH) by Affecting SREBP-1c/PNPLA-3 Pathway via PPAR-α

Nonalcoholic steatohepatitis (NASH) is liver inflammation and a major threat to public health. Several pharmaceutical agents have been used for NASH therapy but their high-rate side effects limit the use. Blueberry juice and probiotics (BP) have anti-inflammation and antibacterial properties, and may be potential candidates for NASH therapy. To understand the molecular mechanism, Sprague Dawley rats were used to create NASH models and received different treatments. Liver tissues were examined using HE (hematoxylin and eosin) and ORO (Oil Red O) stain, and serum biochemical indices were measured. The levels of peroxisome proliferators-activated receptor (PPAR)-α, sterol regulatory element binding protein-1c (SREBP-1c), Patatin-like phospholipase domain-containing protein 3 (PNPLA-3), inflammatory cytokines and apoptosis biomarkers in liver tissues were measured by qRT-PCR and Western blot. HE and ORO analysis indicated that the hepatocytes were seriously damaged with more and larger lipid droplets in NASH models while BP reduced the number and size of lipid droplets (p < 0.05). Meanwhile, BP increased the levels of SOD (superoxide dismutase), GSH (reduced glutathione) and HDL-C (high-density lipoprotein cholesterol), and reduced the levels of AST (aspartate aminotransferase), ALT (alanine aminotransferase), TG (triglycerides), LDL-C (low-density lipoprotein cholesterol) and MDA (malondialdehyde) in NASH models (p < 0.05). BP increased the level of PPAR-α (Peroxisome proliferator-activated receptor α), and reduced the levels of SREBP-1c (sterol regulatory element binding protein-1c) and PNPLA-3 (Patatin-like phospholipase domain-containing protein 3) (p < 0.05). BP reduced hepatic inflammation and apoptosis by affecting IL-6 (interleukin 6), TNF-α (Tumor necrosis factor α), caspase-3 and Bcl-2 in NASH models. Furthermore, PPAR-α inhibitor increased the level of SREBP-1c and PNPLA-3. Therefore, BP prevents NASH progression by affecting SREBP-1c/PNPLA-3 pathway via PPAR-α.