Non-alcoholic fatty liver disease (NAFLD) is a dominant cause of chronic liver disease, but the exact mechanism of progression from simple steatosis to nonalcoholic steatohepatitis (NASH) remains unknown. Here, we investigated the role of exosomes in NAFLD progression. Exosomes were isolated from a human hepatoma cell line treated with palmitic acid (PA) and their miRNA profiles examined by microarray. The human hepatic stellate cell (HSC) line (LX-2) was then treated with exosome isolated from hepatocytes. Compared with controls, PA-treated hepatocytes displayed significantly increased CD36 and exosome production. The microarray analysis showed there to be distinctive miRNA expression patterns between exosomes from vehicle- and PA-treated hepatocytes. When LX-2 cells were cultured with exosomes from PA-treated hepatocytes, the expression of genes related to the development of fibrosis were significantly amplified compared to those treated with exosomes from vehicle-treated hepatocytes. In conclusion, PA treatment enhanced the production of exosomes in these hepatocytes and changed their exosomal miRNA profile. Moreover, exosomes derived from PA-treated hepatocytes caused an increase in the expression levels of fibrotic genes in HSCs. Therefore, exosomes may have important roles in the crosstalk between hepatocytes and HSCs in the progression from simple steatosis to NASH.

Background and Aims:  In a previous study, the authors found that reduced expression of peroxisome proliferator‐activated receptor (PPAR)‐α might play an important role in developing nonalcoholic fatty liver disease (NAFLD). The aim of this study was to analyze the effects of PPAR‐α and ‐γ agonists on NAFLD and verify the mechanisms underlying the PPAR‐α and ‐γ agonist‐induced improvements by evaluating the hepatic gene expression profile involved in fatty‐acid metabolism, using the Otsuka–Long Evans–Tokushima fatty (OLETF) rat.Methods:  Rats were assigned to a control group (group I), fatty liver group (group II), PPAR‐α agonist treatment group (group III), or PPAR‐γ agonist treatment group (group IV). Fasting blood glucose, total cholesterol, and triglycerides were measured. Liver tissues from each group were processed for histological and gene expression analysis. mRNAs of enzymes involved in fatty‐acid metabolism and tumor necrosis factor (TNF)‐α were measured.Results:  After 28 weeks treatment with PPAR‐α or ‐γ agonist, steatosis of the liver was improved in groups III and IV compared with group II. Fasting blood glucose levels were significantly lower in groups III and IV than in group II. In group III, mRNA expression of fatty‐acid β‐oxidation enzymes, such as fatty‐acid transport protein (FATP), fatty‐acid binding protein, carnitine palmitoyltransferase II, medium‐chain acyl‐CoA dehydrogenase (MCAD), long‐chain acyl‐CoA dehydrogenase, and acyl‐CoA oxidase, was significantly increased. However, the treatment‐induced modulation of fatty‐acid β‐oxidation enzymes was confined to FATP and MCAD in group IV. TNF‐α tended to be reduced in groups III and IV compared with group II.Conclusions:  Treatment with PPAR agonists, especially a PPAR‐α agonist, improved the histological and biochemical parameters in the OLETF rat model by inducing fatty‐acid metabolic enzymes.

Our earlier multicenter randomized controlled trial showed that adjuvant immunotherapy with cytokine-induced killer (CIK) cells resulted in longer recurrence-free survival (RFS) and overall survival (OS) as well in patients who received curative treatment for hepatocellular carcinoma (HCC). In the present study, we determined if the efficacy of CIK cell therapy continued after end of repeated CIK cell injections. We performed a follow-up study of our preceding trial. We included 226 patients: 114 patients in the immunotherapy group (injection of 6.4 × 10⁹ CIK cells, 16 times during 60 weeks) and 112 patients in the control group (no treatment) after potentially curative treatment for HCC. In total, 162 patients (89 of the immunotherapy group and 73 of controls) underwent an extended follow-up for 60 months after randomization of the last patient. The primary endpoint was RFS, and secondary endpoints included OS. During follow-up time of median 68.5 months (interquartile range 45.0–82.2 months), the immunotherapy group continued to show a significantly lower risk of recurrence or death [hazard ratio (HR) 0.67; 95% confidence interval (CI) 0.48–0.94; P = 0.009 by one-sided log-rank test]. At 5 years, RFS rate was 44.8% in the immunotherapy group and 33.1% in the control group. The risk of all-cause death was also lower in the immunotherapy group compared to the control group (HR 0.33; 95% CI 0.15–0.76; P = 0.006). In patients who received curative treatment for HCC, the significant improvement in RFS and OS as a result of adjuvant CIK cell immunotherapy lasted over 5 years without boosting.

AIM: To evaluate the inflammasome activation and the effect of peroxisome proliferator-activated receptors (PPAR)-δ agonist treatment in nonalcoholic fatty liver disease (NAFLD) models. METHODS: Male C57BL/6J mice were classified according to control or high fat diet (HFD) with or without PPAR-δ agonist (GW) over period of 12 wk [control, HFD, HFD + lipopolysaccharide (LPS), HFD + LPS + GW group]. HepG2 cells were exposed to palmitic acid (PA) and/or LPS in the absence or presence of GW. RESULTS: HFD caused glucose intolerance and hepatic steatosis. In mice fed an HFD with LPS, caspase-1 and interleukin (IL)-1β in the liver were significantly increased. Treatment with GW ameliorated the steatosis and inhibited overexpression of pro-inflammatory cytokines. In HepG2 cells, PA and LPS treatment markedly increased mRNA of several nucleotide-binding and oligomerization domain-like receptor family members (NLRP3, NLRP6, and NLRP10), caspase-1 and IL-1β. PA and LPS also exaggerated reactive oxygen species production. All of the above effects of PA and LPS were reduced by GW. GW also enhanced the phosphorylation of AMPK-α. CONCLUSION: PPAR-δ agonist reduces fatty acid-induced inflammation and steatosis by suppressing inflammasome activation. Targeting the inflammasome by the PPAR-δ agonist may have therapeutic implication for NAFLD.

Han Ah Lee, Joon Young Jung, Young-Sun Lee, Young Kul Jung, Ji Hoon Kim, Hyonggin An, Hyung Joon Yim, Yoon Tae Jeen, Jong Eun Yeon, Kwan Soo Byun, Soon Ho Um, and Yeon Seok Seo. Gut and Liver 2021;15:599-605. https://doi.org/10.5009/gnl20171