As a promising new target, miR-233 may regulate oxidative stress by targeting keap1-Nrf2 system to affect the pathological process of liver injury in T2DM. Ellagic acid (EA) is versatile for protecting oxidative stress damage and metabolic disorders. In the present study, we investigated the effect of EA on oxidative stress and insulin resistance in high glucose-induced T2DM HepG2 cells and examined the role of miR-223/keap1-Nrf2 pathway in system. HepG2 cells were incubated in 30 mM of glucose, with or without EA (15 and 30 μM) or metformin (Met, 150 μM) for 12 h. Glucose consumption, phosphorylation of IRS1, Akt and ERK under insulin stimulation, ROS and O2- production, MDA level, SOD activity and miR-223 expression, as well as protein levels of keap1, Nrf2, HO-1, SOD1 and SOD2 were analyzed. Furthermore, dual luciferase reporter assay, miR-223 mimic and inhibitor were implemented in cellular studies to explore the possible mechanism. EA upregulated glucose consumption, IRS1, Akt and ERK phosphorylation under insulin stimulation, reduced ROS and O2- production and MDA level, and increased SOD activity in high glucose-exposed HepG2 cells. In addition, EA elevated miR-223 expression level, downregulated mRNA and protein levels of keap1, and upregulated Nrf2, HO-1, SOD1 and SOD2 protein levels in this cell model. What's more, dual luciferase reporter assay, miR-223 mimic and inhibitor transfection confirmed that EA activated keap1-Nrf2 system via elevating miR-223. The miR-223, a negative regulator of keap1, represents an attractive therapeutic target in hepatic injury in T2DM. EA ameliorates oxidative stress and insulin resistance via miR-223-mediated keap1-Nrf2 activation in high glucose-induced T2DM HepG2 cells.

This study examines the effects of chicoric acid (CA) on nonalcoholic fatty liver disease (NAFLD) in high-fat-diet- (HFD-) fed C57BL/6 mice. CA treatment decreased body weight and white adipose weight, mitigated hyperglycemia and dyslipidemia, and reduced hepatic steatosis in HFD-fed mice. Moreover, CA treatment reversed HFD-induced oxidative stress and inflammation both systemically and locally in the liver, evidenced by the decreased serum malondialdehyde (MDA) abundance, increased serum superoxide dismutase (SOD) activity, lowered in situ reactive oxygen species (ROS) in the liver, decreased serum and hepatic inflammatory cytokine levels, and reduced hepatic inflammatory cell infiltration in HFD-fed mice. In addition, CA significantly reduced lipid accumulation and oxidative stress in palmitic acid- (PA-) treated HepG2 cells. In particular, we identified AMPK as an activator of Nrf2 and an inactivator of NFκB. CA upregulated AMPK phosphorylation, the nuclear protein level of Nrf2, and downregulated NFκB protein level both in HFD mice and PA-treated HepG2 cells. Notably, AMPK inhibitor compound C blocked the regulation of Nrf2 and NFκB, as well as ROS overproduction mediated by CA in PA-treated HepG2 cells, while AMPK activator AICAR mimicked the effects of CA. Similarly, Nrf2 inhibitor ML385 partly blocked the regulation of antioxidative genes and ROS overproduction by CA in PA-treated HepG2 cells. Interestingly, high-throughput pyrosequencing of 16S rRNA suggested that CA could increase Firmicutes-to-Bacteroidetes ratio and modify gut microbial composition towards a healthier microbial profile. In summary, CA plays a preventative role in the amelioration of oxidative stress and inflammation via the AMPK/Nrf2/NFκB signaling pathway and shapes gut microbiota in HFD-induced NAFLD.

Ambient air particulate matter (PM) represents a class of heterogeneous substances present in polluted air, which contains many harmful components. Exposure to ambient particulate matter in fine rages (PM_2.5) is associated with non-alcoholic fatty liver disease (NAFLD). Loquat Leaf possesses pharmacological actions on NAFLD. As the main biological active ingredients, the potential therapeutic role of total flavonoids (TF) isolated from Loquat Leaf in PM_2.5-induced NAFLD model remains unclear. The present study was designed to explore the hepatoprotective effect of TF in PM_2.5-induced NAFLD mice with its related mechanisms of action. Mice were exposed to PM_2.5 to induce NAFLD, and body weight, the ratio of liver to body weight, and blood lipids increased significantly compared with the control group. It was found that TF significantly reduced the above parameters in PM_2.5-induced NAFLD mice. TF treatment alleviated oxidative stress by preventing the accumulation of oxidative product malondialdehyde (MDA) and by strengthening the anti-oxidative capacity of superoxide dismutase (SOD). TF was also found to reduce the alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activity in the PM_2.5 group. In addition, TF repaired the PM_2.5-induced decline of insulin receptor substrate-1 (IRs-1) and protein kinase B (Akt) phosphorylation. Meanwhile, the data showed TF suppressed the expression of cytochrome P450 2E1(CYP2E1) and the phosphorylation of c-jun N-terminal kinase (JNK) in PM_2.5-induced NAFLD. Taken together, these findings show that TF alleviate PM_2.5-induced NAFLD via regulation of IRs-1/Akt and CYP2E1/JNK pathways, which may have potential for further development as novel therapeutic agents for NAFLD.