Aiming Liu

Saikosaponin d protects against acetaminophen-induced hepatotoxicity by inhibiting NF-κB and STAT3 signaling

Overdose of acetaminophen (APAP) can cause acute liver injury that is sometimes fatal, requiring efficient pharmacological intervention. The traditional Chinese herb Bupleurum falcatum has been widely used for the treatment of several liver diseases in eastern Asian countries, and saikosaponin d (SSd) is one of its major pharmacologically-active components. However, the efficacy of Bupleurum falcatum or SSd on APAP toxicity remains unclear. C57/BL6 mice were administered SSd intraperitoneally once daily for 5days, followed by APAP challenge. Biochemical and pathological analysis revealed that mice treated with SSd were protected against APAP-induced hepatotoxicity. SSd markedly suppressed phosphorylation of nuclear factor kappa B (NF-κB) and signal transducer and activator of transcription 3 (STAT3) and reversed the APAP-induced increases in the target genes of NF-κB, such as pro-inflammatory cytokine Il6 and Ccl2, and those of STAT3, such as Socs3, Fga, Fgb and Fgg. SSd also enhanced the expression of the anti-inflammatory cytokine Il10 mRNA. Collectively, these results demonstrate that SSd protects mice from APAP-induced hepatotoxicity mainly through down-regulating NF-κB- and STAT3-mediated inflammatory signaling. This study unveils one of the possible mechanisms of hepatoprotection caused by Bupleurum falcatum and/or SSd.

Fenofibrate Metabolism in the Cynomolgus Monkey using Ultraperformance Liquid Chromatography-Quadrupole Time-of-Flight Mass Spectrometry-Based Metabolomics

Fenofibrate, widely used for the treatment of dyslipidemia, activates the nuclear receptor, peroxisome proliferator-activated receptor α. However, liver toxicity, including liver cancer, occurs in rodents treated with fibrate drugs. Marked species differences occur in response to fibrate drugs, especially between rodents and humans, the latter of which are resistant to fibrate-induced cancer. Fenofibrate metabolism, which also shows species differences, has not been fully determined in humans and surrogate primates. In the present study, the metabolism of fenofibrate was investigated in cynomolgus monkeys by ultraperformance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOFMS)-based metabolomics. Urine samples were collected before and after oral doses of fenofibrate. The samples were analyzed in both positive-ion and negative-ion modes by UPLC-QTOFMS, and after data deconvolution, the resulting data matrices were subjected to multivariate data analysis. Pattern recognition was performed on the retention time, mass/charge ratio, and other metabolite-related variables. Synthesized or purchased authentic compounds were used for metabolite identification and structure elucidation by liquid chromatographytandem mass spectrometry. Several metabolites were identified, including fenofibric acid, reduced fenofibric acid, fenofibric acid ester glucuronide, reduced fenofibric acid ester glucuronide, and compound X. Another two metabolites (compound B and compound AR), not previously reported in other species, were characterized in cynomolgus monkeys. More importantly, previously unknown metabolites, fenofibric acid taurine conjugate and reduced fenofibric acid taurine conjugate were identified, revealing a previously unrecognized conjugation pathway for fenofibrate.

Geniposide Inhibits Alpha-Naphthylisothiocyanate-Induced Intrahepatic Cholestasis: The Downregulation of STAT3 and NFκB Signaling Plays an Important Role

Traditional medicinal formulation of Yin-zhi-huang (YZH) is widely used in the clinic for the treatment of jaundice and chronic liver diseases in East Asian countries. However, the pharmacologically active components of YZH and the underlying mechanism are still unknown. Geniposide (GEN) was recently identified as one of the most abundant circulating components in YZH. In this study, we investigated the protective effect of GEN against liver injuries induced by alpha-naphthylisothiocyanate (ANIT). 50[Formula: see text]mg/kg of GEN was administered to ICR mice once daily for 5 days, and challenge of ANIT 75[Formula: see text]mg/kg was performed on the 4th day. Blood and liver tissues were collected on day 6 and subjected to biochemical, histopathological and pathway analyses. The biochemical and pathological findings showed that GEN almost totally attenuated ANIT-induced cholestasis and liver injury compared with the vehicle/ANIT group. The altered gene transcription related to bile acid metabolism and transport was normalized by co-treatment with GEN. The expressions of tumor necrosis factor-[Formula: see text] and the suppressor of cytokine signaling 3 were significantly decreased in the GEN/ANIT group. Western blot revealed that GEN inhibited the activation and expression of STAT3 and NF[Formula: see text]B. These data suggest GEN inhibits ANIT-induced hepatotoxicity. The protective effect is associated with the downregulation of STAT3 and NF[Formula: see text]B signaling.

Schisandrol B protects against cholestatic liver injury through pregnane X receptors

Currently, ursodeoxycholic acid and obeticholic acid are the only two FDA‐approved drugs for cholestatic liver diseases. Thus, new therapeutic approaches need to be developed. Here we have evaluated the anti‐cholestasis effects of Schisandrol B (SolB), a bioactive compound isolated from Schisandra sphenanthera.

Oral administration of nano-titanium dioxide particle disrupts hepatic metabolic functions in a mouse model

TiO2 nano-particle (TiO2 NP) is widely used in industrial, household necessities, as well as medicinal products. However, the effect of TiO2 NP on liver metabolic function has not been reported. In this study, after mice were orally administered TiO2 NP (21nm) for 14days, the serum and liver tissues were assayed by biochemical analysis, real time quantitative polymerase chain reaction, western blot and transmission electron microscopy. The serum bilirubin was increased in a dose dependent manner. Deposition of TiO2 NP in hepatocytes and the abnormality of microstructures was observed. Expression of metabolic genes involved in the endogenous and exogenous metabolism was modified, supporting the toxic phenotype. Collectively, oral administration of TiO2 NP (21nm) led to deposition of particles in hepatocytes, mitochondrial edema, and the disturbance of liver metabolism function. These data suggested oral administration disrupts liver metabolic functions, which was more sensitive than regular approaches to detect material hepatotoxicity. This study provided useful information for risk analysis and regulation of TiO2 NPs by administration agencies.

Biphasic Regulation of Intracellular Calcium by Gemfibrozil Contributes to Inhibiting L6 Myoblast Differentiation: Implications for Clinical Myotoxicity

Gemfibrozil is the most myotoxic fibrate drug commonly used for dyslipidemia, but the mechanism is poorly understood. The current study revealed that gemfibrozil inhibits myoblast differentiation through the regulation of intracellular calcium ([Ca(2+)]i) as revealed in L6 myoblasts by use of laser scan confocal microscopy and flow cytometry using Fluo-4 AM as a probe. Gemfibrozil at 20-400 μM, could regulate [Ca(2+)]i in L6 cells in a biphasic manner, and sustained reduction was observed when the concentration reached 200 μM. Inhibition of L6 differentiation by gemfibrozil was concentration-dependent with maximal effect noted between 200 and 400 μM, as indicated by creatine kinase activities and the differentiation index, respectively. In differentiating L6 myoblasts, gemfibrozil at concentrations below 400 μM led to no significant signs of apoptosis or cytotoxicity, whereas differentiation, inhibited by 200 μM gemfibrozil, was only partially recovered. A good correlation was noted between gemfibrozil concentrations that regulate [Ca(2+)]i and inhibit L6 myoblasts differentiation, and both are within the range of total serum concentrations found in the clinic. These data suggest a potential pharmacodynamic effect of gemfibrozil on myogenesis as a warning sign, in addition to the complex pharmacokinetic interactions. It is also noteworthy that mobilization of [Ca(2+)]i by gemfibrozil may trigger complex biological responses besides myocyte differentiation. Information revealed in this study explores the mechanism of gemfibrozil-induced myotoxicity through the regulation of intracellular calcium.

Inhibition of JNK signalling mediates PPARα‐dependent protection against intrahepatic cholestasis by fenofibrate

Fenofibrate, a PPARα agonist, is the most widely prescribed drug for treating hyperlipidaemia. Although fibrate drugs are reported to be beneficial for cholestasis, their underlying mechanism has not been determined.

Chlorogenic acid inhibits cholestatic liver injury induced by α-naphthylisothiocyanate: involvement of STAT3 and NFκB signalling regulation

Chlorogenic acid (CGA) is one of the most widely consumed polyphenols in diets and is recognized to be a natural hepatoprotective agent. Here, we evaluated the protective effect and the potential mechanism of CGA against ɑ‐naphthylisothiocyanate (ANIT)‐induced cholestasis and liver injury.

Pregnane X Receptor Regulates Liver Size and Liver Cell Fate via Yes‐associated Protein Activation

Activation of pregnane X receptor (PXR), a nuclear receptor that controls xenobiotic and endobiotic metabolism, is known to induce liver enlargement, but the molecular signals and cell types responding to PXR‐induced hepatomegaly remain unknown. In this study, the effect of PXR activation on liver enlargement and cell change was evaluated in several strains of genetically modified mice and animal models. Lineage labeling using AAV‐Tbg‐Cre‐treated Rosa26EYFP mice or Sox9‐CreERT, Rosa26EYFP mice was performed and Pxr‐null mice or AAV Yap short hairpin RNA (shRNA)‐treated mice were used to confirm the role of PXR or yes‐associated protein (YAP). Treatment with selective PXR activators induced liver enlargement and accelerated regeneration in wild‐type (WT) and PXR‐humanized mice, but not in Pxr‐null mice, by increase of cell size, induction of a regenerative hybrid hepatocyte (HybHP) reprogramming, and promotion of hepatocyte and HybHP proliferation. Mechanistically, PXR interacted with YAP and PXR activation induced nuclear translocation of YAP. Blockade of YAP abolished PXR‐induced liver enlargement in mice. Conclusion: These findings revealed a function of PXR in enlarging liver size and changing liver cell fate by activation of the YAP signaling pathway. These results have implications for understanding the physiological functions of PXR and suggest the potential for manipulation of liver size and liver cell fate.

Basal PPARα inhibits bile acid metabolism adaptation in chronic cholestatic model induced by α-naphthylisothiocyanate

Cholestasis is one of the most challenging diseases to be treated in current hepatology. However little is known about the adaptation difference and the underlying mechanism between acute and chronic cholestasis. In this study, wild-type and Pparα-null mice were orally administered diet containing 0.05% ANIT to induce chronic cholestasis. Biochemistry, histopathology and serum metabolome analysis exhibited the similar toxic phenotype between wild-type and Pparα-null mice. Bile acid metabolism was strongly adapted in Pparα-null mice but not in wild-type mice. The Shp and Fxr mRNA was found to be doubled in cholestatic Pparα-null mice compared with the control group. Western blot confirmed the up-regulated expression of FXR in Pparα-null mice treated with ANIT. Inflammation was found to be stronger in Pparα-null mice than those in wild-type mice in chronic cholestasis. These data chain indicated that bile acid metabolism and inflammation signaling were different between wild-type and Pparα-null mice developing chronic cholestasis, although their toxic phenotypes could not be discriminated. So basal PPARα cross-talked with FXR and inhibited bile acid metabolism adaptation in chronic cholestasis.