Upregulation of SIRT1-AMPK by thymoquinone in hepatic stellate cells ameliorates liver injury.

Thymoquinone (TQ) is a biologically active compound isolated from the seeds of Nigella sativa L. (Ranuculaceae). This study investigated the hepato-protective effect of TQ on liver injury through AMP-activated protein kinase (AMPK) signaling in hepatic stellate cells (HSCs). In vitro, TGF-β time-dependently attenuated liver kinase B-1 (LKB1) and AMPK phosphorylation, which were blocked by pretreatment with TQ and AICAR (an activator of AMPK). TQ significantly inhibited collagen-Ι, α-SMA, TIMP-1 and enhanced MMP-13 expression, contributing to prevent TGF-β-induced human HSCs activation. Moreover, TQ induced peroxisome proliferator activated receptor-γ (PPAR-γ) expression, which was inhibited by genetic deletion of AMPK. In vivo, C57BL/6 mice were fed with ethanol diet for 10 days, then administering a single dose of ethanol (5g/kg body weight) via gavage. TQ (20 or 40mg/kg) were given by gavage every day. TQ attenuated the increases in serum aminotransferase and hepatic triglyceride in mice fed with ethanol, while significantly activated LKB1 and AMPK phosphorylation. In addition, TQ enhanced the sirtuin 1 (SIRT1) expression. In conclusion, we demonstrate that AMPK pathway is a key therapeutic target for controlling liver injury and TQ confers hepato-protection against TGF-β-induced the activation of HSCs and ethanol-induced liver injury.

Yang Y ，Bai T ，Yao YL ，Zhang DQ ，Wu YL ，Lian LH ，Nan JX ... -  《-》

Thymoquinone Attenuates Acetaminophen Overdose-Induced Acute Liver Injury and Inflammation Via Regulation of JNK and AMPK Signaling Pathway.

Cui BW ，Bai T ，Yang Y ，Zhang Y ，Jiang M ，Yang HX ，Wu M ，Liu J ，Qiao CY ，Zhan ZY ，Wu YL ，Kang DZ ，Lian LH ，Nan JX ... -  《-》

Anti-fibrotic effect of thymoquinone on hepatic stellate cells.

Hepatic stellate cells (HSCs) are the major cell type involved in the production of extracellular matrix in liver. After liver injury, HSCs undergo transdifferentiation process from quiescent state to activated state, which plays an important role in liver fibrosis. Previous studies have shown that thymoquinone (TQ) might have protective effect against liver fibrosis in animal models; however, the underlying mechanism of action is not fully understood. The aim of this study is to examine whether TQ has any direct effect on HSCs. Our results showed that pretreatment of mice with TQ has protective effect against CCl4-induced liver injury compared to control group (untreated), which is consistent with previous studies. Moreover, our in vivo study showed that COL1A1 and α-SMA mRNA levels were significantly downregulated by TQ treatment. Similarly, in vitro study confirmed that TQ downregulated COL1A1, COL3A1 and α-SMA mRNA levels in activated rat HSCs and LX2 cells, an immortalized human hepatic stellate cell line. Pretreatment with TQ also inhibited the LPS-induced proinflammatory response in LX2 cells as demonstrated by reduced mRNA expression of IL-6 and MCP-1. Mechanistically, inactivation of NF-κB pathway is likely to play a role in the TQ-mediated inhibition of proinflammatory response in HSCs. Finally, we have shown that TQ inhibited the culture-triggered transdifferentiation of freshly isolated rat HSCs as shown by significant downregulation of mRNA expression of several fibrosis-related genes. In conclusion, our study suggests that TQ has a direct effect on HSCs, which may contribute to its overall antifibrotic effect.

Ghazwani M ，Zhang Y ，Gao X ，Fan J ，Li J ，Li S ... -  《-》

Betulin alleviated ethanol-induced alcoholic liver injury via SIRT1/AMPK signaling pathway.

The present study was conducted to investigate the protective effect of betulin, a triterpene from the bark of Betula platyphylla Suk, against ethanol-induced alcoholic liver injury and its possible underlying mechanisms. In vitro, human hepatic stellate cell line, LX-2 cells were treated with betulin (6.25, 12.5 and 25 μM) prior to ethanol (50mM) for 24h. Cell viability was analyzed by methyl thiazolyl tetrazolium assay, protein expressions were assessed by Western blot. In vivo, we induced alcoholic liver injury in male C57BL/6 mice, placing them on Lieber-DeCarli ethanol-containing diets for 10 days and then administering a single dose of ethanol (5 g/kg body weight) via gavage. Betulin (20 and 50mg/kg) were given by gavage every day. In vitro results showed that betulin effectively decreased LX-2 cell viability, attenuated collagen-I, α-smooth muscle actin (α-SMA) levels, activated liver kinase B-1 (LKB1) and adenosine monophosphate-activated protein kinase (AMPK) phosphorylation. Betulin suppressed the expression of sterol regulatory element-binding protein-1 (SREBP-1), and genetic deletion of AMPK blocked the effect of betulin on SREBP-1 in ethanol treated LX-2 cells. In vivo, betulin attenuated the increases in serum aminotransferase and triglyceride levels in the mice fed with chronic-binge ethanol, while significantly inhibited SREBP-1 expression and activated LKB1-AMPK phosphorylation. Additionally, betulin enhanced the sirtuin 1 (SIRT1) expression mediated by ethanol. Taken together, betulin alleviates alcoholic liver injury possibly through blocking the regulation of SREBP-1 on fatty acid synthesis and activating SIRT1-LKB1-AMPK signaling pathway.

Bai T ，Yang Y ，Yao YL ，Sun P ，Lian LH ，Wu YL ，Nan JX ... -  《-》

Thymoquinone alleviates thioacetamide-induced hepatic fibrosis and inflammation by activating LKB1-AMPK signaling pathway in mice.

The current study was conducted to investigate the anti-fibrotic effect and its possible underlying mechanisms of thymoquinone (TQ) against hepatic fibrosis in vivo. TQ is the major active compound derived from the medicinal Nigella sativa. Liver fibrosis was induced in male Kunming mice by intraperitoneal injections of thioacetamide (TAA, 200 mg/kg). Mice were treated concurrently with TAA alone or TAA plus TQ (20 mg/kg or 40 mg/kg) given daily by oral gavage. Our data demonstrated that TQ treatment obviously reversed liver tissue damage compared with TAA alone group, characterized by less inflammatory infiltration and accumulation of extracellular matrix (ECM) proteins. TQ significantly attenuated TAA-induced liver fibrosis, accompanied by reduced protein and mRNA expression of α-smooth muscle actin (α-SMA), collagen-І and tissue inhibitor of metalloproteinase-1 (TIMP-1). TQ downregulated the expression of toll-like receptor 4 (TLR4) and remarkably decreased proinflammatory cytokine levels as well. TQ also significantly inhibited phosphatidylinositol 3-kinase (PI3K) phosphorylation. Furthermore, TQ enhanced the phosphorylation adenosine monophosphate-activated protein kinase (AMPK) and liver kinase B (LKB)-1. In conclusion, TQ may reduce ECM accumulation, and it may be at least regulated by phosphorylation of AMPK signaling pathways, suggesting that TQ may be a potential candidate for the therapy of hepatic fibrosis.

Bai T ，Yang Y ，Wu YL ，Jiang S ，Lee JJ ，Lian LH ，Nan JX ... -  《-》