Ginsenoside 25-OCH3-PPD Promotes Activity of LXRs To Ameliorate P2X7R-Mediated NLRP3 Inflammasome in the Development of Hepatic Fibrosis.

Ginseng is widely used in energy drinks, dietary supplements, and herbal medicines, and its pharmacological actions are related with energy metabolism. As an important modulating energy metabolism pathway, liver X receptors (LXRs) can promote the resolving of hepatic fibrosis and inflammation. The present study aims to evaluate the regulation of 25-OCH3-PPD, a ginsenoside isolated from Panax ginseng, against hepatic fibrosis and inflammation in thioacetamide (TAA)-stimulated mice by activating the LXRs pathway. 25-OCH3-PPD decreases serum ALT/AST levels and improves the histological pathology of liver in TAA-induced mice; attenuates transcripts of pro-fibrogenic markers associated with hepatic stellate cell activation; attenuates the levels of pro-Inflammatory cytokines and blocks apoptosis happened in liver; inhibits NLRP3 inflammasome by affecting P2X7R activation; and regulates PI3K/Akt and LKB1/AMPK-SIRT1. 25-OCH3-PPD also facilitates LX25Rs and FXR activities decreased by TAA stimulation. 25-OCH3-PPD also decreases α-SMA via regulation of LXRs and P2X7R-NLRP3 in vitro. Our data suggest the possibility that 25-OCH3-PPD promotes activity of LXRs to ameliorate P2X7R-mediated NLRP3 inflammasome in the development of hepatic fibrosis.

Potentiation of hepatic stellate cell activation by extracellular ATP is dependent on P2X7R-mediated NLRP3 inflammasome activation.

Purinergic receptor P2x7 (P2x7R) is a key modulator of liver inflammation and fibrosis. The present study aimed to investigate the role of P2x7R in hepatic stellate cells activation. Lipopolysaccharide (LPS) or the conditioned medium (CM) from LPS-stimulated RAW 264.7 mouse macrophages was supplemented to human hepatic stellate cells, LX-2 for 24h and P2x7R selective antagonist A438079 (10µM) was supplemented to LX-2 cells 1h before LPS or CM stimulation. In addition LX-2 cells were primed with LPS for 4h and subsequently stimulated for 30min with 3mM of adenosine 5'-triphosphate (ATP). A438079 was supplemented to LX-2 cells 10min prior to ATP. Directly treated with LPS on LX-2 cells, mRNA expressions of interleukin (IL)-1ß, IL-18 and IL-6 were increased, as well as mRNA expressions of P2x7R, caspase-1, apoptosis-associated speck-like protein containing CARD (ASC) and NOD-like receptor family, pyrin domain containing 3 (NLRP3) mRNA. LPS also increased α-smooth muscle actin (α-SMA) and type I collagen mRNA expressions, as well as collagen deposition. Interestingly treatment of LX-2 cells with LPS-activated CM exhibited the greater increase of above factors than those in LX-2 cells directly treated with LPS. Pretreatment of A438079 on LX-2 cells stimulated by LPS or LPS-activated CM both suppressed IL-1ß mRNA expression. LPS combined with ATP dramatically increased protein synthesis and cleavage of IL-1ß and its mRNA level than those in HSC treated with LPS or ATP alone. Additionally LX-2 cells primed with LPS and subsequently stimulated for 30min with ATP greatly increased mRNA and protein expression of caspase-1, NLRP3 and P2x7R, as well as liver fibrosis markers, α-SMA and type I collagen. These events were remarkably suppressed by A438079 pretreatment. siRNA against P2x7R reduced protein expression of NLRP3 and α-SMA, and suppressed deposition and secretion of type I collagen. The involvement of P2X7R-mediated NLRP3 inflammasome activation in IL-1ß production of HSC might contribute to ECM deposition and suggests that blockade of the P2x7R-NLRP3 inflammasome axis represents a potential therapeutic target to liver fibrosis.

Cucurbitacin E ameliorates hepatic fibrosis in vivo and in vitro through activation of AMPK and blocking mTOR-dependent signaling pathway.

The study evaluated the potential protective effect and underlying mechanism of Cucurbitacin E (CuE) in both thioacetamide-induced hepatic fibrosis and activated HSCs. CuE inhibited the proliferation of activated HSC/T-6 cells in a concentration- and time-dependent manner; triggered the activation of caspase-3, cleaved PARP, altered ratio of bcl-2-to-bax, and affected cytochrome C protein in a time- and concentration-dependent manner. CuE arrested activated HSCs at the G2/M phase. Furthermore, CuE reduced levels of p-Erk/MAPK and also inhibited the protein and mRNA expressions of α-SMA, TIMP-1 and collagen I in activated HSC-T6 cells. CuE inhibited PI3K and Akt phosphorylation, and reduced the levels of p-mTOR and p-P70S6K and increased the expression of p-AMPK, which is similar with AICAR and metformin. C57BL/6 mice were intraperitoneally injected with thioacetamide (TAA) for five continuous weeks (100 or 200mg/kg, three times per week) along with daily administration of CuE (5 or 10mg/kg/d) and curcumin (Cur, 20mg/kg). CuE treatments significantly reduced serum ALT/AST levels, α-SMA, TIMP-1, and collagen I protein expressions. HE, Masson trichrome, Sirius red and immunohistochemical staining also suggested that CuE could ameliorate hepatic fibrosis. Our findings suggest that CuE induces apoptosis of activated HSC and ameliorates TAA-induced hepatic fibrosis through activation of AMPK and blocking mTOR-dependent signaling pathway.

Acanthoic acid, a diterpene in Acanthopanax koreanum, ameliorates the development of liver fibrosis via LXRs signals.

Liver X receptors (LXRs)-mediated signals in acanthoic acid (AA) ameliorating liver fibrosis were examined in carbon tetrachloride (CCl4)-induced mice and TGF-ß stimulated hepatic stellate cells (HSCs). AA was isolated from the root of Acanthopanax koreanum Nakai (Araliaceae). CCl4-treated mice were intraperitoneally injected with 10% CCl4 in olive oil (2 mL/kg for 8 weeks). In AA treated groups, mice were intragastrically administrated with AA (20 mg/kg or 50 mg/kg) 3 times per week for 8 weeks. Administration of AA reduced serum aminotransferase and tissue necrosis factor-α (TNF-α) levels evoked by CCl4, and the reverse of liver damage was further confirmed by histopathological staining. Administration of AA reduced the expression of fibrosis markers and regulated the ratio of MMP-13/TIMP-1, further reversed the development of liver fibrosis. TGF-ß (5 ng/ml) was added to activate HSC-T6 cells for 2 h, and then treated with AA (1, 3, or 10 µmol/l) for 24 h before analysis. Cells were collected and proteins were extracted to detect the expressions of LXRs. AA could inhibit the expression of α-SMA stimulated by TGF-ß and increase the expression of LXRß. In vivo and in vitro experiments, AA could modulate liver fibrosis induced by CCl4-treatment via activation of LXRα and LXRß, while inhibit HSCs activation only via activation of LXRß. Acanthoic acid might ameliorate liver fibrosis induced by CCl4 via LXRs signals.