Silibinin Inhibits Proliferation and Migration of Human Hepatic Stellate LX-2 Cells

Artemsieverlides A-M, diverse sesquiterpenoid dimers with antihepatic fibrosis activity isolated from Artemisia sieversiana based on molecular networking

Artemsieverlides A-M (1-13), undescribed sesquiterpenoid dimers, were isolated from Artemisia sieversiana (Asteraceae) under the guidance of antihepatic fibrosis activity and molecular networking. Their structures were elucidated by spectral data (HRESIMS, UV, IR, 1D and 2D NMR), and ECD calculations. Of them, compounds 3, 7 and 12 were unambiguously confirmed by the single-crystal X-ray diffraction. Structurally, the sesquiterpenoid dimers are classified into three types, involving one guaiane-eudesmane, one guaiane-1,10-seco-guaiane, and 11 guaiane dimers. Artemsieverlides C-F are the first examples of guaiane dimers fused via C-1/C-2' and C-3/C-3' single bonds, which suggest chemical diversity of sesquiterpenoid dimers in A. sieversiana. Antihepatic fibrosis assay suggested that most of the compounds displayed inhibitory activity on HSC-LX2. The most active artemsieverlide K (11) gave an IC50 value of 58.6 μM, which was 2 times more active than the positive drug silybin (IC50, 133.7 μM).

Inhibition of hepatic stellate cell activation by nutraceuticals: an emphasis on mechanisms of action

Liver diseases emerge as a serious threat to humans worldwide due to increasing morbidity and mortality. Liver disease related deaths accounts for one third of all disease related death globally. A simple fatty liver if unattended advances further to liver fibrosis, cirrhosis and hepatocellular carcinoma. During liver fibrogenesis, hepatic stellate cells gets activated into myofibroblast like cells and exhibit proliferative and fibrogenic features. Targeting these activated hepatic stellate cells offer promising therapeutic approach towards liver fibrosis management. To date there is no Food and Drug Administration approved treatments for liver fibrosis. However, a large number of clinical trials are being conducted employing monoclonal antibodies, drugs, dietary supplements and herbal medicines. A vast number of research findings demonstrated nutraceuticals to be effective against experimental liver fibrosis both in vitro and in vivo. Nutraceuticals typically regulate key signaling pathways in activated hepatic stellate cells and exhibit anti-fibrotic effect. In this review, the mechanistic action of nutraceuticals targeting activated hepatic stellate cells were summarized to establish them as a possible therapeutic candidate for liver fibrosis.

Synthesis, characterization, and in vitro-in ovo toxicological screening of silibinin fatty acids conjugates as prodrugs with potential biomedical applications

Silibinin (SIL), the most active phytocompound from Silybum marianum (L.), exerts many biological effects but has low stability and bioavailability. To overcome these drawbacks, the current research proposed the synthesis of silibilin oleate (SIL-O) and silibilin linoleate (SIL-L) derivatives as prodrugs with potentially optimized properties for biomedical applications, and the establishment of their in vitro-in ovo safety profiles. The physicochemical characterization of the obtained compounds using density functional theory (DFT) calculations, and Raman and 1H liquid-state nuclear magnetic resonance (NMR) spectroscopy confirmed the formation of SIL-O and SIL-L complexes. Computational predictions revealed that these lipophilic derivatives present a lower drug-likeness score (-29.96 for SIL-O and -23.55 for SIL-L) compared to SIL, but an overall positive drug score (0.07) and no risk for severe adverse effects. SIL-O and SIL-L showed no cytotoxicity or impairment in cell migration at low concentrations, but at the highest concentration (100 μM), they displayed distinct toxicological profiles. SIL-L was more cytotoxic (on cardiomyoblasts - H9c2(2-1), hepatocytes - HepaRG, and keratinocytes - HaCaT) than SIL-O or SIL, significantly inhibiting cell viability (<60%), altering cellular morphology, reducing cell confluence (<70%), and inducing prominent apoptotic-like nuclear features. At the concentration of 100 μM, SIL-O presented an irritation score (IS) of 0.61, indicating a lack of irritant effect on the chorioallantoic membrane (CAM), while SIL-L was classified as a slight irritant with an IS of 1.99. These findings outline a more favorable in vitro and in ovo biocompatibility for SIL-O compared to SIL L, whose applications are dosage limited due to potential toxicity.

Superporous sponge prepared by secondary network compaction with enhanced permeability and mechanical properties for non-compressible hemostasis in pigs

Developing superporous hemostatic sponges with simultaneously enhanced permeability and mechanical properties remains challenging but highly desirable to achieve rapid hemostasis for non-compressible hemorrhage. Typical approaches to improve the permeability of hemostatic sponges by increasing porosity sacrifice mechanical properties and yield limited pore interconnectivity, thereby undermining the hemostatic efficacy and subsequent tissue regeneration. Herein, we propose a temperature-assisted secondary network compaction strategy following the phase separation-induced primary compaction to fabricate the superporous chitosan sponge with highly-interconnected porous structure, enhanced blood absorption rate and capacity, and fatigue resistance. The superporous chitosan sponge exhibits rapid shape recovery after absorbing blood and maintains sufficient pressure on wounds to build a robust physical barrier to greatly improve hemostatic efficiency. Furthermore, the superporous chitosan sponge outperforms commercial gauze, gelatin sponges, and chitosan powder by enhancing hemostatic efficiency, cell infiltration, vascular regeneration, and in-situ tissue regeneration in non-compressible organ injury models, respectively. We believe the proposed secondary network compaction strategy provides a simple yet effective method to fabricate superporous hemostatic sponges for diverse clinical applications.

Novel Nano-Based Drug Delivery Systems Targeting Hepatic Stellate Cells in the Fibrotic Liver

Hepatic stellate cells (HSCs) exist in the liver’s perisinusoidal space, are phenotypically activated, and acquire myofibroblast-like phenotype. This phenotypic transformation is accountable for the accumulation and production of various extracellular matrix (ECM) proteins, involving different fibril-forming collagens in the perisinusoidal space, producing altered hepatic function and portal hypertension and increased vascular resistance, fibrosis, cirrhosis, and hepatocellular carcinoma. The activated HSCs/myofibroblasts are principal collagen-producing cells in the damaged liver. Therefore, fibrosis treatments are often targeting HSCs. HSCs store most of the total body’s retinol in their cytoplasm, and hence, antifibrotic nanomedicines are often targeted with vitamin A decoration. Vitamin A-decorated nanomedicines with siRNAs for transforming growth factor-beta, collagen, and connective tissue growth factors target to inhibit fibrogenesis and the ECM-associated gene expressions, leading to fibrosis regression. Similarly, a variety of miRNAs play pro- and antifibrotic function. In the fibrotic liver, the profibrotic miRNAs are targeted with their respective antagomir and the antifibrotic miRNAs are targeted with their respective agomirs along with HSC-specific nanodecoration. These miRNA treatments reduce fibrogenesis by downregulation of ECM-related gene expressions. However, liver fibrosis is caused by the upregulation of a different type of profibrotic signaling pathways associated with ECM accumulation in the fibrotic liver. Therefore, specific gene silencing by siRNAs or targeting particularly miRNA may also not effectively reduce fibrosis to a greater extent. However, nanodecoration of a drug is useful to deliver drugs into activated HSCs in the injured liver. Therefore, the aim of this review is to focus on targeted drug delivery towards activated HSCs in the persistently damaged liver.

Hepatic stellate cells in the injured liver: Perspectives beyond hepatic fibrosis

Over the last two decades, our understanding of the pathological role of hepatic stellate cells (HSCs) in fibrotic liver disease has increased dramatically. As HSCs are identified as the principal collagen-producing cells in the injured liver, several experimental and clinical studies have targeted HSCs to treat liver fibrosis. However, HSCs also play a critical role in developing nonfibrotic liver diseases such as cholestasis, portal hypertension, and hepatocellular carcinoma (HCC). Therefore, this review exclusively focuses on the role of activated HSCs beyond hepatic fibrosis. In cholestasis conditions, elevated bile salts and bile acids activate HSCs to secrete collagen and other extracellular matrix products, which cause biliary fibrosis and cholangitis. In the chronically injured liver, autocrine and paracrine signaling from liver sinusoidal endothelial cells activates HSCs to induce portal hypertension via endothelin-1 release. In the tumor microenvironment (TME), activated HSCs are the major source of cancer-associated fibroblasts (CAF). The crosstalk between activated HSC/CAF and tumor cells is associated with tumor cell proliferation, migration, metastasis, and chemoresistance. In TME, activated HSCs convert macrophages to tumor-associated macrophages and induce the differentiation of dendritic cells (DCs) and monocytes to regulatory DCs and myeloid-derived suppressor cells, respectively. This differentiation, in turn, increases T cells proliferation and induces their apoptosis leading to reduced immune surveillance in TME. Thus, HSCs activation in chronically injured liver is a critical process involved in the progression of cholestasis, portal hypertension, and liver cancer.

Hepatotoxic potentials of methotrexate: Understanding the possible toxicological molecular mechanisms

Methotrexate (MTX) is one of the most effective and widely used drugs in the management of autoimmune and dermatological diseases. Rheumatoid arthritis and psoriasis patients who are under long term MTX-therapy are at high risk of developing a liver injury. Accumulation of intracellular MTX-polyglutamate (MTX-PG), a metabolite of MTX triggers oxidative stress, inflammation, steatosis, fibrosis, and apoptosis in hepatocytes. MTX-PG causes oxidative stress in the liver by inducing lipid peroxidation thereby releasing reactive oxygen species and suppressing antioxidant response elements. MTX-PG induces several pro-inflammatory signaling pathways and cytokines such as tumor necrosis factor-α, nuclear factor kappa B and interleukin 6 (IL-6), IL- β1, IL-12. MTX-PG depletes hepatic folate level and decreases RNA and DNA synthesis leading to hepatocyte death. MTX-PG inhibits 5-aminoimidazole-4-carboxamide ribonucleotide transformylase enzyme and thereby causes accumulation of intracellular adenosine, which causes activation of hepatic stellate cells, extracellular matrix accumulation and hepatic fibrosis. MTX-PG induces hepatocytes apoptosis by activation of caspase 3 via the intrinsic pathway. Clinically, aggravation of underlying fatty liver to non-alcoholic steatohepatitis with fibrosis seems to be an important mechanism of liver injury in MTX-treated RA patients. Therefore, there is a need for monitoring liver injury in RA, psoriatic and cancer patients with NAFLD and fibrosis risk factors during MTX treatment. This review summarizes the possible molecular mechanism of MTX-induced hepatotoxicity. It may pave the way for early detection of liver injury and develop novel strategies for treating MTX mediated hepatotoxicity.

Ameliorative effects of Qingganjiuwei powder, a traditional Mongolian medicine, against CCl4-induced liver fibrosis in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Qingganjiuwei powder (QGJWS) is a well-known traditional drug containing nine kinds of medicinal materials. This drug is commonly used in the Inner Mongolia region and exerts remarkable clinical effects on hepatic protection.

AIM OF THE STUDY

To investigate whether QGJWS inhibits liver fibrosis in rats and to reveal its potential mechanisms.

METHODS

Liver fibrosis model was induced by CCl₄ for 8 weeks in SD rats. Next, rats were intragastrically administered quantum satis doses of QGJWS (0.525, 1.575, 4.725 g/kg per day) or Silymarin (SIL; 120 mg/kg per day) for 8 weeks. Afterwards, the rats were sacrificed, and serum aminotransferase (ALT and AST) levels, histopathological changes as well as the mRNA and protein expression of matrix metalloproteinase 2 (MMP2), MMP9, tissue inhibitor of metalloproteinase1 (TIMP1), collagen type Ⅰ(COL1), α-smooth muscle actin (α-SMA), combined with phosphorylation levels of extracellular signal-regulated kinase (ERK), C-Jun amino-terminal kinases (JNKs) and stress-activated protein kinase-2 (p38) protein in liver tissues were measured in each groups, respectively.

RESULTS

The symptoms and signs of the model rats were consistent with the diagnostic criteria of liver fibrosis. By contrast, treatment with QGJWS clearly improved the general condition of rats. Also, the morphology and structure of liver can be ameliorated, there are fewer hepatocyte necrosis and lymphocytic infiltration and pseudolobuli in QGJWS treatment groups as demonstrated by histopathological analysis, thus helping bring about lower METAVIR scores. QGJWS administration also dramatically decreased serum ALT and AST levels. Further immunohistochemistry, western blotting and Real-Time PCR analysis revealed that QGJWS significantly enhanced the mRNA and protein expression of MMP2, MMP9, and downregulated the expression levels of COL1, TIMP1 and α-SMA. Furthermore, QGJWS reduced the activities of mitogen-activated protein kinases (MAPKs) pathway in liver by inhibited the phosphorylation of ERK, JNKs and p38 proteins.

CONCLUSIONS

QGJWS offers notable protection against CCl₄-induced liver fibrosis in rats, which may be due to its ability to inhibited the MAPKs signaling pathway.

Advantages and challenges in nanomedicines for chronic liver diseases: A hepatologist's perspectives

Chronic liver diseases (CLD) are responsible for significant morbidity and mortality worldwide. CLD patients are at a high risk of developing progressive liver fibrosis, cirrhosis, hepatocellular carcinoma (HCC), and subsequent liver failure. To date, there is no specific and effective therapies exist for patients with various forms of CLD. The application of nanotechnology has emerged as a rapidly developing area of interest for the safe and target-specific delivery of poorly aqueous soluble hepatoprotective agents and nucleic acids (siRNA/miRNAs) in CLD. The nanoparticle combination improves bioavailability and plasma stability of drugs with poor aqueous solubility. However, the extent of successful functional delivery of nanoparticles into hepatocytes is often surprisingly low. High Kupffer cells interaction reduces the nanomedicine efficacy. During fibrosis, the extracellular matrix accumulation in the perisinusoidal space restricts nanoparticle delivery to hepatocytes. The availability and uptake of nanoparticles exposure to different cells in the liver microenvironment is as Kupffer cells > sinusoidal endothelial cells > HSCs > hepatocytes. The most widely used strategy to reduce nanoparticles and macrophages interaction is to coat the particle surface with polyethylene glycol. The cationic charged nanoparticles have increased hepatocyte delivery by increased cellular interaction by disrupting the endosomal system via their pH buffering capacity. The immune clearance and toxicity of nanoparticles are mainly unpredictable. Therefore, more elaborate knowledge on exact cellular uptake and intracellular accumulation, trafficking, and endosomal sorting of nanoparticle is the need of the hour to improve the rational carrier design.

Novel Heme Oxygenase-1 (HO-1) Inducers Based on Dimethyl Fumarate Structure

Novel heme oxygenase-1 (HO-1) inducers based on dimethyl fumarate (DMF) structure are reported in this paper. These compounds are obtained by modification of the DMF backbone. Particularly, maintaining the α, β-unsaturated dicarbonyl function as the central chain crucial for HO-1 induction, different substituted or unsubstituted phenyl rings are introduced by means of an ester or amide linkage. Symmetric and asymmetric derivatives are synthesized. All compounds are tested on a human hepatic stellate cell line LX-2 to assay their capacity for modifying HO-1 expression. Compounds 1b, 1l and 1m stand out for their potency as HO-1 inducers, being 2–3 fold more active than DMF, and for their ability to reverse reactive oxygen species (ROS) production mediated using palmitic acid (PA). These properties, coupled with a low toxicity toward LX-2 cell lines, make these compounds potentially useful for treatment of diseases in which HO-1 overexpression may counteract inflammation, such as hepatic fibrosis. Docking studies show a correlation between predicted binding free energy and experimental HO-1 expression data. These preliminary results may support the development of new approaches in the management of liver fibrosis.

Cytotoxic potentials of silibinin assisted silver nanoparticles on human colorectal HT-29 cancer cells

It is of interest to study the cytotoxicity of silibinin assisted silver nanoparticles in human colorectal (HT-29) cancer cells. Silver nanoparticles were synthesized using silibinin as a reducing agent. The synthesized silibinin assisted silver nanoparticles ( SSNPs) were characterized and analyzed using a transmission electron microscope and spectrophotometer. The SSNPs synthesized in this study are spherical and their size ranges from 10 to 80 nm. HT-29 cells were treated with different concentrations (2, 4, 6, 8 and 10 ng/mL) of SSNPs and cytotoxicity was evaluated. The apoptosis was using flow cytometry. p53 protein expression using western blot. SSNPs are induced a decrease in viability and increased concentration-dependent cytotoxicity in HT-29 cells. SSNPs treatment also caused apoptosis-related morphological changes. SSNPs treatments at 8 and 16 ng/ml showed a prominent apoptotic change i.e., 70.3% and 83.6% respectively, and decreased viability of HT-29 cells 20% and 11.2% respectively as compared to control cells. SSNPs treatments induced p53 expression in HT-29 cells. Data shows that SSNPs have the potential to induce apoptosis in colorectal cancer cells. This provides insights for the further evaluation of SSNPs in fighting colon cancer.

Endothelin-1 in portal hypertension: The intricate role of hepatic stellate cells

IMPACT STATEMENT

Portal hypertension is pathologically defined as increase of portal venous pressure, mainly due to chronic liver diseases such as fibrosis and cirrhosis. In fibrotic liver, activated hepatic stellate cells increase their contraction in response to endothelin-1 (ET-1) via autocrine and paracrine stimulation from liver sinusoidal endothelial cells and injured hepatocytes. Clinical studies are limited with ET receptor antagonists in cirrhotic patients with portal hypertension. Hence, studies are needed to find molecules that block ET-1 synthesis. Accumulation of extracellular matrix proteins in the perisinusoidal space, tissue contraction, and alteration in blood flow are prominent during portal hypertension. Therefore, novel matrix modulators should be tested experimentally as well as in clinical studies. Specifically, tumor necrosis factor-α, transforming growth factor-β1, Wnt, Notch, rho-associated protein kinase 1 signaling antagonists, and peroxisome proliferator-activated receptor α and γ, interferon-γ and sirtuin 1 agonists should be tested elaborately against cirrhosis patients with portal hypertension.

Silibinin Triggers the Mitochondrial Pathway of Apoptosis in Human Oral Squamous Carcinoma Cells

Background:

Silibinin, a natural polyphenolic flavonoid present in seed extracts of milk thistle (Silybum marianum). It has been shown to interact with various cancer-related cell signalling pathways in preclinical models, demonstrating promising anticancer effects in vitro and in vivo.

Materials and Methods:

The cytotoxic effect of silibinin was evaluated in human oral squamous carcinoma (SCC-25) cells by MTT assay. The apoptosis-related morphological changes were investigated by AO/EB dual staining. The cytochrome c, caspases-3, and -9, B-cell lymphoma-2 (Bcl-2), and B-cell associated X protein (Bax) gene expressions were analysed by PCR.

Results:

We have shown that silibinin treatment for 24 h in SCC-25 cells induced cytotoxicity in a concentration-dependent manner. The cytotoxic potential was due to the induction of apoptosis via the release of mitochondrial cytochrome c into the cytosol and subsequent activation of caspases-3 and -9. Dual staining assay was further confirmed the induction of early apoptosis upon silibinin treatment.

Conclusion:

The results from this study show that silibinin can be considered as a promising drug candidate for the treatment of oral squamous cell carcinoma.

Gentiopicroside Ameliorates the Progression from Hepatic Steatosis to Fibrosis Induced by Chronic Alcohol Intake

In current study, we aimed to investigate whether the gentiopicroside (GPS) derived from Gentiana manshurica Kitagawa could block the progression of alcoholic hepatic steatosis to fibrosis induced by chronic ethanol intake. C57BL/6 mice were fed an ethanol-containing Lieber-DeCarli diet for 4 weeks. LX-2 human hepatic stellate cells were treated with GPS 1 h prior to transforming growth factor-β (TGF-β) stimulation, and murine hepatocyte AML12 cells were pretreated by GPS 1 h prior to ethanol treatment. GPS inhibited the expression of type I collagen (collagen I), α-smooth muscle actin (α-SMA) and tissue inhibitor of metal protease 1 in ethanol-fed mouse livers with mild fibrosis. In addition, the imbalanced lipid metabolism induced by chronic ethanol-feeding was ameliorated by GPS pretreatment, characterized by the modulation of lipid accumulation. Consistently, GPS inhibited the expression of collagen I and α-SMA in LX-2 cells stimulated by TGF-β. Inhibition of lipid synthesis and promotion of oxidation by GPS were also confirmed in ethanol-treated AML12 cells. GPS could prevent hepatic steatosis advancing to the inception of a mild fibrosis caused by chronic alcohol exposure, suggesting GPS might be a promising therapy for targeting the early stage of alcoholic liver disease.

An Evaluation of the In Vitro Roles and Mechanisms of Silibinin in Reducing Pyrazinamide- and Isoniazid-Induced Hepatocellular Damage

Tuberculosis remains a significant infectious lung disease that affects millions of patients worldwide. Despite numerous existing drug regimens for tuberculosis, drug-induced liver injury is a major challenge that limits the effectiveness of these therapeutics. Two drugs that form the backbone of the commonly administered quadruple antitubercular regimen, that is, pyrazinamide (PZA) and isoniazid (INH), are associated with such hepatotoxicity. Yet, we lack safe and effective alternatives to the antitubercular regimen. Consequently, current research largely focuses on exploiting the hepatoprotective effect of nutraceutical compounds as complementary therapy. Silibinin, a herbal product widely believed to protect against various liver diseases, potentially provides a useful solution given its hepatoprotective mechanisms. In our study, we identified silibinin's role in mitigating PZA- and INH-induced hepatotoxicity and elucidated a deeper mechanistic understanding of silibinin's hepatoprotective ability. Silibinin preserved the viability of human foetal hepatocyte line LO2 when co-administered with 80 mM INH and decreased apoptosis induced by a combination of 40 mM INH and 10 mM PZA by reducing oxidative damage to mitochondria, proteins, and lipids. Taken together, this proof-of-concept forms the rational basis for the further investigation of silibinin's hepatoprotective effect in subsequent preclinical studies and clinical trials.

Cellular and molecular effects of silymarin on the transdifferentiation processes of LX-2 cells and its connection with lipid metabolism

Fibrosis process in the liver is a clinical condition established in response to chronic lesions and may be reversible in many situations. In this process, hepatic stellate cells (HSCs) activate and produce extracellular matrix compounds. During fibrosis, the lipid metabolism is also altered and contributes to the transdifferentiation of the HSCs. Thus, controlling lipid metabolism in HSCs is suggested as a method to control or reverse the fibrotic condition. In the search for therapies that modulate lipid metabolism and treat liver diseases, silymarin has been identified as a relevant natural compound to treat liver pathologies. The present study aimed to evaluate the cellular and molecular effects of silymarin in the transdifferentiation process of HSCs (LX-2) from activated phenotype to a more quiesced-like cells , also focusing on understanding the modulatory effects of silymarin on lipid metabolism of HSCs. In our analyses, 100 µM of silymarin reduced the synthesis of actin filaments in activated cells, the synthesis of the protein level of α-SMA, and other pro-fibrotic factors such as CTGF and PFGF. The concentration of 150 µM silymarin did not reverse the activation aspects of LX-2 cells. However, both evaluated concentrations of the natural compound protected the cells from the negative effects of dimethyl sulfoxide (DMSO). Furthermore, we evaluated lipid-related molecules correlated to the transdifferentiation process of LX-2, and 100 µM of silymarin demonstrated to control molecules associated with lipid metabolism such as FASN, MLYCD, ACSL4, CPTs, among others. In contrast, cellular incubation with 150 µM of silymarin increased the synthesis of long-chain fatty acids and triglycerides, regarding the higher presence of DMSO (v/v) in the solvent. In conclusion, silymarin acts as a hepatoprotective agent and modulates the pro-fibrogenic stimuli of LX-2 cells, whose effects depend on stress levels in the cellular environment.

β-Sitosterol attenuates carbon tetrachloride-induced oxidative stress and chronic liver injury in rats

Chronic liver diseases are clinically silent and responsible for significant morbidity and mortality worldwide. β-Sitosterol (BSS), major phytosterol in plants, has a wide spectrum of protective effect against various chronic ailments. We investigated the hepatoprotective effect of BSS against carbon tetrachloride (CCl₄)-induced chronic liver injury in rats. Thirty rats were divided into five groups, with six animals in each group. Group I rats served as control while groups II, III, IV, and V rats were injected intraperitoneally with CCl₄ (0.2 mL/100 g b.w. in olive oil (1:1)) for 7 consecutive weeks. After 7 weeks, group II rats were left without any treatments and served as CCl₄ alone group, while groups III, IV, and V rats were treated with BSS 25 and 50 mg/kg b.w. and silymarin 100 mg/kg b.w. as oral post-treatments respectively, for the next 4 weeks. At the end of the experiment, hepatotoxicity marker enzymes in serum, oxidative stress, and fibrosis marker were analyzed. CCl₄ administration caused significant elevation of marker enzymes of hepatotoxicity in serum and increased lipid peroxidation and fibrosis markers such as hydroxyproline, collagen, α-smooth muscle actin, vimentin, desmin, and matrix metalloproteinases 9 in liver tissue of rats. This treatment also caused a significant diminution of intracellular enyzmic antioxidants such as SOD and CAT in the liver tissue of rats. All the above adversities were significantly mitigated by the BSS post-treatments. The results suggest that BSS could have a hepatoprotective effect against oxidative stress-mediated CLD induced by CCl₄.

Galewone, an Anti-Fibrotic Polyketide from Daldinia eschscholzii with an Undescribed Carbon Skeleton

A novel polyphenolic natural product, galewone, with undescribed carbon skeleton, was isolated as a racemate from the culture of Daldinia eschscholzii IFB-TL01, a fungus obtained from the mantis (Tenodera aridifolia) gut. The galewone structure was elucidated by a combination of MS and NMR spectra, and substantiated by X-ray crystallographic diffraction. The absolute stereochemistry of each galewone enantiomers was determined by the CD spectrum. In compliance of the structural similarities, galewone might be the shunt products of the dalesconol biosynthetic pathway. Both (−)- and ( + )-galewones were evaluated to be anti-fibrotic against activated hepatic stellate cell line, CFSC-8B, with the IC₅₀ values being 3.73 ± 0.21 and 10.10 ± 0.41 μM, respectively. Thus, galewone may serve as a starting molecule for the discovery of new anti-fibrotic drug.

Hepatic fibrosis: It is time to go with hepatic stellate cell-specific therapeutic targets

Hepatic fibrosis is a pathological lesion, characterized by the progressive accumulation of extracellular matrix (ECM) in the perisinusoidal space and it is a major problem in chronic liver diseases. Phenotypic activation of hepatic stellate cells (HSC) plays a central role in the progression of hepatic fibrosis. Retardation of proliferation and clearance of activated HSCs from the injured liver is an appropriate therapeutic strategy for the resolution and treatment of hepatic fibrosis. Clearance of activated HSCs from the injured liver by autophagy inhibitors, proapoptotic agents and senescence inducers with the high affinity toward the activated HSCs may be the novel therapeutic strategy for the treatment of hepatic fibrosis in the near future.

Oxidative stress is bane in chronic liver diseases: Clinical and experimental perspective

Oxidative stress plays an important role in the pathogenesis of various chronic liver diseases (CLD) and increasing evidence have confirmed the contributory role of oxidative stress in the pathogenesis of drugs and chemical-induced CLD. Chronic liver injury is manifested as necrosis, cholestasis, fibrosis, and cirrhosis. Chronic administration of anti-tubercular, anti-retroviral, immunosuppressive drugs is reported to induce free radical generation during their biotransformation in the liver. Further, these reactive intermediates are said to induce profibrogenic cytokines, several inflammatory markers, collagen synthesis during the progression of hepatic fibrosis. Oxidative stress and free radicals are reported to induce activation and proliferation of hepatic stellate cells in the injured liver leading to the progression of CLD. Hence, to counteract or to scavenge these reactive intermediates, several plant-derived antioxidant principles have been effectively employed against oxidative stress and came out with promising results in human and experimental models of CLD. This review summarizes the relationships between oxidative stress and different liver pathogenesis induced by drugs and xenobiotics, focusing upon different chronic liver injury induced by alcohol, antitubercular drugs and hyperactivity of antiretroviral drugs in HIV patients, viral hepatitis infection induced oxidative stress.

Silibinin Restores NAD⁺ Levels and Induces the SIRT1/AMPK Pathway in Non-Alcoholic Fatty Liver

Nicotinamide adenine dinucleotide (NAD⁺) homeostasis is emerging as a key player in the pathogenesis of non-alcoholic fatty liver disease (NAFLD) and is tightly linked to the SIRT1/5’-AMP-activated protein kinase (AMPK) pathway. Silibinin, the main component of silymarin, has been proposed as a nutraceutical for the treatment of NAFLD. In this study, we aimed to identify whether silibinin may influence the NAD⁺/SIRT1 axis. To this end, C57BL/6 mice were fed a high fat diet (HFD) for 16 weeks, and were treated with silibinin or vehicle during the last 8 weeks. HepG2 cells were treated with 0.25 mM palmitate for 24 h with silibinin 25 µM or vehicle. HFD and palmitate administration led to oxidative stress, poly-(ADP-ribose)-polymerase (PARP) activation, NAD⁺ consumption, and lower SIRT1 activity. In mice fed the HFD, and in HepG2 treated with palmitate, we consistently observed lower levels of phospho-AMPK^Thr172 and phospho-acetyl-CoA carboxylase^Ser79 and higher levels of nuclear sterol regulatory element-binding protein 1 activity, indicating de novo lipogenesis. Treatment of mice and HepG2 with silibinin abolished oxidative stress, and inhibited PARP activation thus restoring the NAD⁺ pool. In agreement with preserved NAD⁺ levels, SIRT1 activity and AMPK phosphorylation returned to control levels in mice and HepG2. Our results further indicate silibinin as a promising molecule for the treatment of NAFLD.

Evaluation of HepaRG cells for the assessment of indirect drug-induced hepatotoxicity using INH as a model substance

HepaRG cells are widely used as an in vitro model to assess drug-induced hepatotoxicity. However, only few studies exist so far regarding their suitability to detect the effects of drugs requiring a preceding activation via the cytochrome P450 (CYP) system. A prototypic substance is the anti-tuberculosis agent INH, which is metabolized into N-acetylhydrazine, which then triggers hepatotoxicity. Therefore, the aim of the present study was to test if this effect can also be detected in HepaRG cells and if it can be counteracted by the known hepatoprotectant silibinin. For this purpose, differentiated HepaRG cells were treated with increasing concentrations of INH (0.1-100 mM) or 10 mM INH plus escalating concentrations of silibinin (1-100 µM). After 48 h of treatment, cell morphology and parameters indicating cell vitality, oxidative stress, and liver cell function were assessed. High concentrations of INH led to severe histopathological changes, reduced cell vitality and glutathione content, increased LDH and ASAT release into the medium, enhanced lipid peroxidation, and elevated cleaved caspase-3 expression. Additionally, glycogen depletion and reduced biotransformation capacity were seen at high INH concentrations, whereas at low concentrations an induction of biotransformation enzymes was noticed. Silibinin caused clear-cut protective effects, but with few parameters INH toxicity was even aggravated, most probably due to increased metabolization of INH into its toxic metabolite. In conclusion, HepaRG cells are excellently suited to evaluate the effects of substances requiring prior toxification via the CYP system, such as INH. They additionally enable the identification of complex substance interactions.