An update on the therapeutic role of RNAi in NAFLD/NASH

Unhealthy lifestyles have given rise to a growing epidemic of metabolic liver diseases, including nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH). NAFLD often occurs as a consequence of obesity, and currently, there is no FDA-approved drug for its treatment. However, therapeutic oligonucleotides, such as RNA interference (RNAi), represent a promising class of pharmacotherapy that can target previously untreatable conditions. The potential significance of RNAi in maintaining physiological homeostasis, understanding pathogenesis, and improving metabolic liver diseases, including NAFLD, is discussed in this article. We explore why NAFLD/NASH is an ideal target for therapeutic oligonucleotides and provide insights into the delivery platforms of RNAi and its therapeutic role in addressing NAFLD/NASH.

A new method to induce nonalcoholic steatohepatitis (NASH) in mice

Background

General overnutrition is one of the key factors involved in the development of nonalcoholic fatty liver disease (NAFLD) as the most common liver disease occur by two steps of liver injury ranges from steatosis to nonalcoholic steatohepatitis (NASH). Here the effect of fructose, fat-rich and western diet (WD) feeding was studied along with aggravative effect of cigarette smoking on liver status in mice.

Methods

Sixty-four male NMRI mice were included in this study and assigned into 4 groups that fed standard, fructose-rich, high fat-, and western-diet for 8 weeks and then each group divided in two smoker and nonsmoker subgroups according to smoke exposing in the last 4 weeks of feeding time (n = 8). Histopathological studies, serum biochemical analyses and hepatic TNF-α level were evaluated in mice to compare alone or combination effects of dietary regimen and cigarette smoking.

Results

Serum liver enzymes and lipid profile levels in WD fed mice were significantly higher than in other studied diets. Exposing to cigarette smoke led to more elevation of serum biochemical parameters that was also accompanied by a significant increase in hepatic damage shown as more severe fat accumulation, hepatocyte ballooning and inflammation infiltrate. Elevated TNF-α level confirmed incidence of liver injury.

Conclusion

The finding of this study demonstrated that a combination of cigarette smoke exposure and WD (rich in fat, fructose, and cholesterol) could induce a more reliable mouse model of NASH.

Evaluation of the therapeutic potential effect of Fas receptor gene knockdown in experimental model of non-alcoholic steatohepatitis

Aim: Stimulation of Fas death receptor is introduced as a major cause of non-alcoholic steatohepatitis (NASH) progression through suppression of cell viability. Therefore, the blocking of death pathways is hypothesised to be express new approaches to NASH therapy. For this purpose, current experiment applied synthetic small interference RNA (SiRNA) to trigger Fas death receptor and to show its potential therapeutic role in designed NASH model. Methods: Male mice were placed on a western diet (WD) for 8 weeks and exposed to cigarette smoke during the last 4 weeks of feeding to induce NASH model. In the next step, Fas SiRNA was injected to mice aiming to examine specific Fas gene silencing, after 8 weeks. As a control, mice received scrambled SiRNA. Reversible possibility of disease was examined by 3 weeks of recovery. Results: Analysis of data is accompanied with the significant histopathological changes (steatosis, ballooning and inflammation), increased lipid profile and hepatic enzyme activities (AST, ALT, ALP) plus TBARS as well as decreased antioxidants levels in NASH model. Upon Fas-SiRNA injection, almost all measured parameters of NASH such as overexpression of Fas receptor, caspase3, NF-kB genes and marked increase of hepatic TNF-α were significantly restored and were remained nearly unchanged following recovery liking as scrambled groups. Conclusions: The suppression of Fas receptor signalling subsequent RNAi therapy may represent an applicable strategy to decline hepatocyte damages and so NASH progression in mice.

Prevalence of non-alcoholic fatty liver disease in patients with diabetes mellitus, hyperlipidemia, obesity and polycystic ovary syndrome: A cross-sectional study in north of Iran

BACKGROUND AND AIM

The aim of this study was to describe the frequency of non-alcoholic fatty liver disease (NAFLD) in patients with diabetes mellitus (DM), hyperlipidemia, obesity and polycystic ovaries syndrome (PCOS).

METHODS

In a cross-sectional study, 333 patients who had one of the certain diagnosis of DM, hyperlipidemia, obesity or PCOS were enrolled. Information about demographics, anthropometric, nutritional habitude, smoking history, medical history and physical activity were recorded. Liver ultrasound examination and routine biochemistry analysis were performed.

RESULTS

Among 333 patients with one of the four above-mentioned diseases. 199 patients (59.8%) had NAFLD. Male were more likely to have NAFLD than female (72.8% vs. 50.8% respectively, P < 0.001). About, 80.7% of patients through 41-50 years age had NAFLD. The frequency of abnormal fasting blood glucose, alanine aminotransferase (ALT), triglyceride, and total cholesterol were significantly higher in patients with NAFLD (P < 0.05). Subjects with NAFLD had a higher body mass index than non-NAFLD (33.6 ± 7.9 kg/m² vs. 31.1 ± 5.0 kg/m2 respectively, P = 0.002). Patients with DM, hyperlipidemia, hypertension, and hypothyroidism were more likely to have NAFLD (P < 0.05). Patients with consumption of supper, high-fat diet, enjoy of eating and smoking were more likely to have NAFLD and patients with fruit and vegetable uptake and physical activity were less likely to have NAFLD (P < 0.05).

CONCLUSIONS

As most patients with NAFLD are asymptomatic, employed individuals with higher education levels, with a history of smoking and unhealthy diet along with DM, hyperlipidemia, PCOS and obesity seriously have to be followed and educated for lifestyle modification.