HIF-1α inhibition in macrophages preserves acute liver failure by reducing IL-1ß production.

The development of acute liver failure (ALF) is dependent on its local inducer. Inflammation is a high-frequency and critical factor that accelerates hepatocyte death and liver failure. In response to injury stress, the expression of the transcription factor hypoxia-inducible factor-1α (HIF-1α) in macrophages is promoted by both oxygen-dependent and oxygen-independent mechanisms, thus promoting the expression and secretion of the cytokine interleukin-1ß (IL-1ß). IL-1ß further induces hepatocyte apoptosis or necrosis by signaling through the receptor (IL-1R) on hepatocyte. HIF-1α knockout in macrophages or IL-1R knockout in hepatocytes protects against liver failure. However, whether HIF-1α inhibition in macrophages has a protective role in ALF is unclear. In this study, we revealed that the small molecule HIF-1α inhibitor PX-478 inhibits the expression and secretion of IL-1ß, but not tumor necrosis factor α (TNFα), in bone marrow-derived macrophages (BMDMs). PX-478 pretreatment alleviates liver injury in LPS/D-GalN-induced ALF mice by decreasing the hepatic inflammatory response. In addition, preventive or therapeutic administration of PX-478 combined with TNFα neutralizing antibody markedly improved LPS/D-GalN-induced ALF. Taken together, our data suggest that PX-478 administration leads to HIF-1α inhibition and decreased IL-1ß secretion in macrophages, which represents a promising therapeutic strategy for inflammation-induced ALF.

Cooperative Tertiary Amine/Palladium-Catalyzed Sequential [4 + 3] Cyclization/[1,3]-Rearrangement for Stereoselective Synthesis of Spiro [Methylenecyclopentane-1,3'-oxindolines].

A cooperative tertiary amine/palladium-catalyzed sequential reaction process, proceeding via a [4 + 3] cyclization of isatin-derived Morita-Baylis-Hillman Expansion (MBH) carbonates and tert-butyl 2-(hydroxymethyl)allyl carbonates followed by a [1,3]-rearrangement, has been found and developed. A range of structurally diverse spiro[methylene cyclopentane-1,3'-oxindolines] bearing two adjacent ß,γ-acyl quaternary carbon stereocenters, which are difficult to obtain by conventional strategies, were obtained in good yields. Further synthetic utility of this protocol is highlighted by its excellent regio- and stereocontrol as well as the large-scale synthesis and diverse functional transformations of the synthetic compounds. Moreover, the control experiments probably established the plausible mechanism for this sequential [4 + 3] cyclization/[1,3]-rearrangement process.

AMPK activator C24 inhibits hepatic lipogenesis and ameliorates dyslipidemia in HFHC diet-induced animal models.

Dyslipidemia is a chronic metabolic disease characterized by elevated levels of lipids in plasma. Recently, various studies demonstrate that the increased activity of adenosine 5'-monophosphate-activated protein kinase (AMPK) causes health benefits in energy regulation. Thus, great efforts have been made to develop AMPK activators as a metabolic syndrome treatment. In the present study, we investigated the effects of the AMPK activator C24 on dyslipidemia and the potential mechanisms. We showed that C24 (5-40 µM) dose-dependently increased the phosphorylation of AMPKα and acetyl-CoA carboxylase (ACC), and inhibited lipogenesis in HepG2 cells. Using compound C, an AMPK inhibitor, or hepatocytes isolated from liver tissue-specific AMPK knockout AMPKα1α2fl/fl;Alb-cre mice (AMPK LKO), we demonstrated that the lipogenesis inhibition of C24 was dependent on hepatic AMPK activation. In rabbits with high-fat and high-cholesterol diet-induced dyslipidemia, administration of C24 (20, 40, and 60 mg · kg-1· d-1, ig, for 4 weeks) dose-dependently decreased the content of TG, total cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C) in plasma and played a role in protecting against hepatic dysfunction by decreasing lipid accumulation. A lipid-lowering effect was also observed in high-fat and high-cholesterol diet-fed hamsters. In conclusion, our results demonstrate that the small molecular AMPK activator C24 alleviates hyperlipidemia and represents a promising compound for the development of a lipid-lowering drug.

Development of the novel ACLY inhibitor 326E as a promising treatment for hypercholesterolemia.

Hepatic cholesterol accumulation is an important contributor to hypercholesterolemia, which results in atherosclerosis and cardiovascular disease (CVD). ATP-citrate lyase (ACLY) is a key lipogenic enzyme that converts cytosolic citrate derived from tricarboxylic acid cycle (TCA cycle) to acetyl-CoA in the cytoplasm. Therefore, ACLY represents a link between mitochondria oxidative phosphorylation and cytosolic de novo lipogenesis. In this study, we developed the small molecule 326E with an enedioic acid structural moiety as a novel ACLY inhibitor, and its CoA-conjugated form 326E-CoA inhibited ACLY activity with an IC50 = 5.31 ± 1.2 µmol/L in vitro. 326E treatment reduced de novo lipogenesis, and increased cholesterol efflux in vitro and in vivo. 326E was rapidly absorbed after oral administration, exhibited a higher blood exposure than that of the approved ACLY inhibitor bempedoic acid (BA) used for hypercholesterolemia. Chronic 326E treatment in hamsters and rhesus monkeys resulted in remarkable improvement of hyperlipidemia. Once daily oral administration of 326E for 24 weeks prevented the occurrence of atherosclerosis in ApoE-/- mice to a greater extent than that of BA treatment. Taken together, our data suggest that inhibition of ACLY by 326E represents a promising strategy for the treatment of hypercholesterolemia.

The triterpenoid sapogenin (2α-OH-Protopanoxadiol) ameliorates metabolic syndrome via the intestinal FXR/GLP-1 axis through gut microbiota remodelling.

Gypenosides, extracts of Gynostemma yixingense, have been traditionally prescribed to improve metabolic syndrome in Asian folk and local traditional medicine hospitals. However, the mechanism of its action remains unclarified. In this work, our results indicated that chronic administration of 2α-OH-protopanoxadiol (GP2), a metabolite of gypenosides in vivo, protected mice from high-fat diet-induced obesity and improved glucose tolerance by improving intestinal L-cell function. Mechanistically, GP2 treatment inhibited the enzymatic activity of bile salt hydrolase and modulated the proportions of the gut microbiota, which led to an increase in the accumulation of tauro-ß-muricholic acid (TßMCA) in the intestine. TßMCA induced GLP-1 production and secretion by reducing the transcriptional activity of nuclear receptor farnesoid X receptor (FXR). Transplantation of GP2-remodelled fecal microbiota into antibiotic-treated mice also increased the intestinal TßMCA content and improved intestinal L-cell function. These findings demonstrate that GP2 ameliorates metabolic syndrome at least partly through the intestinal FXR/GLP-1 axis via gut microbiota remodelling and also suggest that GP2 may serve as a promising oral therapeutic agent for metabolic syndrome.