Molecular mechanisms in thioacetamide-induced acute and chronic liver injury models

Thioacetamide (TAA) undergoes bioactivation in the liver by the CYP450 2E1 enzyme, resulting in the formation of TAA-S-oxide and TAA-S-dioxide. TAA-S-dioxide induces oxidative stress via lipid peroxidation of the hepatocellular membrane. A single TAA dose (50-300 mg/kg) administration initiates hepatocellular necrosis around the pericentral region after its covalent binding to macromolecules in the liver. Intermittent TAA administration (150-300 mg/kg, weekly thrice, for 11-16 weeks) activates transforming growth factor (TGF)-β/smad3 downstream signaling in injured hepatocytes, causing hepatic stellate cells (HSCs) to acquire myofibroblast like phenotype. The activated HSCs synthesize a variety of extracellular matrix, leading to liver fibrosis, cirrhosis, and portal hypertension. The TAA induced liver injury varies depending on the animal model, dosage, frequency, and routes of administration. However, TAA induces hepatotoxicity in a reproducible manner, and it is an ideal model to evaluate the antioxidant, cytoprotective, and antifibrotic compounds in experimental animals.

Tricarboxylic Acid Metabolite Imbalance in Rats with Acute Thioacetamide-Induced Hepatic Encephalopathy Indicates Incomplete Recovery

Exposure to the toxin thioacetamide (TAA) causes acute hepatic encephalopathy (HE), changes in the functioning of systemic organs, and an imbalance in a number of energy metabolites. The deferred effects after acute HE development are poorly understood. The study considers the balance of the tricarboxylic acid (TCA) cycle metabolites in the blood plasma, liver, kidneys, and brain tissues of rats in the post-rehabilitation period. The samples of the control (n = 3) and TAA-induced groups of rats (n = 13) were collected six days after the administration of a single intraperitoneal TAA injection at doses of 200, 400, and 600 mg/kg. Despite the complete physiological recovery of rats by this date, a residual imbalance of metabolites in all the vital organs was noted. The results obtained showed a trend of stabilizing processes in the main organs of the animals and permit the use of these data both for prognostic purposes and the choice of potential therapeutic agents.

The Protective Effect of SLNP on Hepatic Fibrosis Induced by Thioacetamide in Rats

INTRODUCTION

The incidence of non-alcoholic fatty liver disease (NAFLD) has increased in recent years. Hepatic fibrosis (HF) is an important step in the progression of NAFLD to cirrhosis and even carcinoma and is also recognized as a possible reversal phase.

AIMS

We previously found that the aqueous extract of Sedum Lineare Thunb. has hepatoprotective effects. This study investigated the hepatoprotective effect and mechanism of the Sedum Lineare Thunb. n-butanol phase (SLNP) on HF in rats.

METHODS

Animals were intraperitoneally injected with thioacetamide solution twice a week for 8 weeks to prepare an HF model and were administered the corresponding drugs or an equal volume of normal saline by intragastric administration once a day for 8 weeks. Liver function, hydroxyproline and malondialdehyde (MDA) content, superoxide dismutase (SOD), Na+-K+-ATPase, and Ca2+-Mg2+-ATPase were analyzed using colorimetric methods. Moreover, mRNA expression and protein levels in the liver tissue were detected via quantitative polymerase chain reaction and western blotting, respectively.

RESULTS

The results showed that SLNP could effectively improve the liver function of rats with HF and significantly reduce the content of hydroxyproline; the mRNA expression and protein levels of alpha-smooth muscle actin (α-SMA), collagen I, III, and IV, transforming growth factor beta 1 (TGF-β1), Smad2/3, and Smad4 were also significantly reduced. Simultaneously, SLNP significantly increased the activities of SOD, Na+-K+- ATPase, and Ca2+-Mg2+-ATPase in the rat liver tissues, whereas it reduced the levels of MDA and SOD in the serum and liver tissues.

CONCLUSION

This study revealed that SLNP elicits an anti-fibrotic effect by inhibiting oxidative stress and stellate cell activation, thereby reducing the formation and deposition of the extracellular matrix. The TGF-β1/Smads signaling pathway may be involved in this process.

Edaravone protects against liver fibrosis progression via decreasing the IL-1β secretion of macrophages

Edaravone (EDA), a strong novel free radical scavenger, have been demonstrated to exert neurovascular protective effects clinically. Furthermore, EDA can suppress the lung injury, pulmonary fibrosis and skin fibrosis, while the precise effects and mechanisms of EDA on liver injury and fibrosis remain unclear. The effects of EDA on the Thioacetamide (TAA)-induced liver fibrosis were evaluated by sirius red staining, α-SMA immunohistochemistry. The percentages of immune cell subsets were analyzed by flow cytometry. Immunofluorescence assay was performed to identify the fibrotic properties of hepatic stellate cells (HSCs). Western blot and qPCR were used to detect the levels of liver fibrosis-related molecules and IL-1β. EDA displayed a hepatic protective role in TAA-induced chronic liver fibrosis via inhibiting monocyte/macrophages recruitment and IL-1β production of macrophages. Mechanically, EDA inhibited of NF-κB signal pathway and reactive oxygen species (ROS) production in macrophages. Moreover, EDA treatment indirectly suppressed the activation of HSCs by decreasing the IL-1β secretion of macrophages. Together, EDA protects against TAA-induced liver fibrosis via decreasing the IL-1β production of macrophages, thereby providing a feasible solution for clinical treatment of liver fibrosis.

Model of Liver Fibrosis Induction by Thioacetamide in Rats for Regenerative Therapy Studies

Hepatic fibrosis is caused by chronic injury due to toxic, infectious, or metabolic causes, and it may progress to cirrhosis and hepatocellular carcinoma. There is currently no antifibrotic therapy authorized for human use; however, there are promising studies using cell therapies. There are also no animal models that exactly reproduce human liver fibrosis that can be used to better understand the mechanisms of its regression and identify new targets for treatment and therapeutic approaches. On the other hand, mesenchymal stem cells (MSC) have experimentally demonstrated fibrosis regression effects, but it is necessary to have an animal model of advanced liver fibrosis to evaluate the effect of these cells. The aim of this work was to establish a protocol for the induction of advanced liver fibrosis in rats using thioacetamide (TAA), which will allow us to perform trials using MSC as a possible therapy for fibrosis regression. For this purpose, we selected 24 female rats and grouped them into three experimental groups: the control group (G-I) without treatment and groups II (G-II) and III (G-III) that received TAA by intraperitoneal injection for 24 weeks. Then, 1 × 106/kg adipose mesenchymal stem cells (ASCs) were infused intravenously. Groups G-I and G-II were sacrificed 7 days after the last dose of ASC, and G-III was sacrificed 8 weeks after the last ASC infusion, all with xylazine/ketamine (40 mg/kg). The protocol used in this work established a model of advanced hepatic fibrosis as corroborated by METAVIR tests of the histological lesions; by the high levels of the markers α-SMA, CD68, and collagen type I; by functional alterations due to elevated markers of the hepatic lesions; and by alterations of the leukocytes, lymphocytes, and platelets. Finally, transplanted cells in the fibrous liver were detected. We conclude that TAA applied using the protocol introduced in this study induces a good model of advanced liver fibrosis in rats.

Molecular mechanisms involved in the effects of morin in experimental hepatic encephalopathy

This study aimed to investigate the possible usefulness of morin flavonoid in comparison to silymarin as a hepatic/neuronal-supportive agent with similar effects and higher bioavailability in a rat model of hepatic encephalopathy (HE). Morin effects on rat liver and brain were evaluated post-induction of HE by thioacetamide (TAA; 200 mg/kg/day for 3 successive days). Then, the serum activities of aspartate transaminase (AST) and alanine transaminase (ALT) together with ammonia concentration were estimated to assess the liver function. Also, the degree of brain effects was evaluated via the assessment of brain contents of reduced glutathione (GSH), malondialdehyde (MDA), tumor necrosis factor-alpha (TNF-α), and interleukin (IL-1β) together with glutathione peroxidase (GPx) activity. In addition, the apoptotic and inflammatory changes in brain and liver tissues were also assessed via immunohistochemical examination. Our findings revealed a promising effect of morin against HE complications; as it corrected the liver functions, attenuated the brain/liver tissue injuries, and reduced the apoptotic and inflammatory insults of HE on both organs. These effects are comparable to those of silymarin. Morin could be introduced as a promising hepato- and neuro-therapeutic adjuvant in HE-associated neuronal complications especially in cases like silymarin intolerance.

Improved anti-fibrotic effects by combined treatments of simvastatin and NS-398 in experimental liver fibrosis models

BACKGROUND/AIMS

Efficient anti-fibrotic therapies are required for the treatment of liver cirrhosis. Hydroxymethylglutaryl-coenzyme A reductase inhibitors (statins) and cyclooxygenase-2 (COX-2) inhibitors have been reported to have anti-fibrotic effects. Here, we investigated whether combined treatment with a statin and a COX-2 inhibitor has synergistic anti-fibrotic effects.

METHODS

The effects of treatment strategies incorporating both simvastatin and a COX-2 inhibitor, NS-398, were investigated using an immortalized human hepatic stellate cell line (LX-2) and a hepatic fibrosis mouse model developed using thioacetamide (TAA) in drinking water. Cellular proliferation was investigated via 5-bromo-2-deoxyuridine uptake. Pro- and anti-apoptotic factors were investigated through Western blotting and real-time polymerase chain reaction analysis.

RESULTS

The evaluation of the anti-proliferative effects on LX-2 cells showed that the observed effects were more pronounced with combination therapy than with single-drug therapy. Moreover, hepatic fibrosis and collagen deposition decreased significantly in TAA-treated mice in response to the combined treatment strategy. The mechanisms underlying the anti-fibrotic effects of the combination therapy were investigated. The effects of the combination therapy were correlated with increased expression levels of extracellular signal-regulated kinase 1/2 signaling molecules, upregulation of the Bax/Bcl-2 signaling pathway, inhibition of the transforming growth factor-β signaling pathway, and inhibition of tissue inhibitor of matrix metalloproteinases 1 and 2.

CONCLUSION

The combination of simvastatin and NS-398 resulted in a synergistic anti-fibrotic effect through multiple pathways. These findings offer a theoretical insight into the possible clinical application of this strategy for the treatment of advanced liver diseases with hepatic fibrosis.

Icariin attenuates thioacetamide‑induced bone loss via the RANKL‑p38/ERK‑NFAT signaling pathway

There is an increasing incidence of destructive bone disease caused by osteoclast proliferation. This is characterized by reduced bone mass and imbalance of bone homeostasis. Icariin (ICA), a flavonoid compound isolated from Epimedium, has anti‑osteoporosis activity and inhibits the formation of osteoclasts and bone resorption. The purpose of the present study was to investigate the protective effect of ICA on osteoclastic differentiation induced by thioacetamide (TAA) and its possible mechanism in Sprague Dawley (SD) rats. In the present study, SD rats were intraperitoneally injected with TAA (300 mg/kg) for the bone loss model, treated with ICA (600 mg/kg, intragastric gavage) in the ICA group and TAA+ICA group for treatment of bone loss for 6 weeks. Indexes associated with bone metabolism, such as alkaline phosphatase, N‑terminal telopeptide of type‑I collagen (NTX‑I), calcium (Ca), phosphorus (P) and magnesium (Mg) in the serum, were detected. Osteoclast differentiation of femoral tissues was detected by hematoxylin and eosin and tartrate‑resistant acid phosphatase staining. The femoral bone mass was evaluated using a three‑point bending test and micro computed tomography. Western blotting was used to detect the expression levels of osteoclast‑related proteins in each group. In the rats treated with TAA, the serum concentrations of Ca, P and Mg were decreased, the serum concentration of NTX‑I was increased, osteoclast differentiation of the femur was increased, femur bone stress and bone mass were decreased and the bone loss and osteoclast formation were reduced after ICA treatment. In addition, ICA inhibited the protein expression of receptor activator of nuclear factor κ‑Β ligand (RANKL), receptor activator of nuclear factor κ‑B (RANK), p38, ERK, c‑Fos and nuclear factor of activated T cells 1 (NFATc1) in the femur of rats treated with TAA. The results suggested that ICA may inhibit osteoclast differentiation by downregulating the RANKL‑p38/ERK‑NFAT signaling pathway and prevent TAA‑induced bone loss. The results are helpful to understand the mechanism of osteoclast differentiation induced by TAA, as well as the antiresorptive activity and molecular mechanism of ICA, and to provide new ideas for the treatment of osteolytic diseases.

Application of Bone Marrow Mesenchymal Stem Cells Effectively Eliminates Endotoxemia to Protect Rat from Acute Liver Failure Induced by Thioacetamide

BACKGROUND

Endotoxemia is related to worse clinical outcomes in acute liver failure (ALF), but its management remains unsatisfactory. In this study, we aimed to assess whether the application of bone marrow mesenchymal stem cells (BMSCs) could eliminate endotoxemia and protect rats against ALF induced by thioacetamide (TAA).

METHODS

BMSCs were isolated from rats and identified by the specific morphology, differentiation potential, and surface markers. The optimal dose of TAA for this study was explored and TAA-induced ALF rats were randomized to three groups: the normal control group (Saline), ALF group (TAA + Saline), and BMSCs-treated group (TAA + BMSCs). The intestinal migration and differentiation of BMSCs was tracked in vivo, and intestinal permeability, endotoxin and inflammatory cytokines, histology, and mortality were analyzed. Moreover, we added the inhibitor of the PI3K/AKT/mTOR signaling pathway into the co-culture system of BMSCs with enterocytes and then performed CK and Villin expression experiments to assess the role of PI3K/AKT/mTOR signal pathway in the intestinal differentiation of BMSCs.

RESULTS

BMSCs migrated to the intestinal injury sites and differentiated into enterocytes, intestinal permeability was decreased compared with the ALF group. The higher expression of endotoxin and inflammatory cytokines were reversed after BMSCs transplantation in rats with ALF. Mortality and intestinal lesion were significantly decreased. Blocking the PI3K/AKT/mTOR signal pathway inhibited BMSCs' intestinal differentiation in vitro.

CONCLUSION

BMSCs can eliminate endotoxemia and reduce mortality in rats with ALF, and the PI3K/AKT/mTOR signal pathway is involved in intestinal differentiation. BMSCs transplantation could be a potential candidate for the treatment of endotoxemia in ALF.

Vitamin D3 supplementation alleviates chemically-induced cirrhosis-associated hepatocarcinogenesis

Vitamin D₃ (VD₃) deficiency has been associated with increased risk for cirrhosis and hepatocellular carcinoma, a highly incident malignant neoplasia worldwide. On the other hand, VD₃ supplementation has shown some beneficial effects in clinical studies and rodent models of chronic liver disease. However, preventive effects of dietary VD₃ supplementation in cirrhosis-associated hepatocarcinogenesis is still unknow. To investigate this purpose, male Wistar rats submitted to a combined diethylnitrosamine- and thioacetamide-induced model were concomitantly supplemented with VD₃ (5,000 and 10,000 IU/kg diet) for 25 weeks. Liver samples were collected for histological, biochemical and molecular analysis. Serum samples were used to measure 25-hydroxyvitamin D [25(OH)D] and alanine aminotransferase levels. Both VD₃ interventions decreased hepatic collagen deposition and pro-inflammatory p65 protein levels, while increased hepatic antioxidant catalase and glutathione peroxidase activities and serum 25(OH)D, without a clear dose-response effect. Nonetheless, only the highest concentration of VD₃ increased hepatic protein levels of VD receptor, while decreased the number of large preneoplastic glutathione-S-transferase- (>0.5 mm²) and keratin 8/18-positive lesions, as well the multiplicity of hepatocellular adenomas. Moreover, this intervention increased hepatic antioxidant Nrf2 protein levels and glutathione-S-transferase activity. In summary, dietary VD₃ supplementation - in special the highest intervention - showed antifibrotic and antineoplastic properties in chemically-induced cirrhosis-associated hepatocarcinogenesis. The positive modulation of Nrf2 antioxidant axis may be mechanistically involved with these beneficial effects, and may guide future clinical studies.

Therapeutic potential of probiotics - Lactobacillus plantarum UBLP40 and Bacillus clausii UBBC07 on thioacetamide-induced acute hepatic encephalopathy in rats

PURPOSE

Hepatic encephalopathy (HE) or hepatic coma is a demanding, not utterly understood complication of acute and chronic liver dysfunction and portosystemic shunting. In HE, hyperammonemia and inflammatory responses are believed to act in synergism. Probiotics, Lactobacillus plantarum UBLP40 and Bacillus clausii UBBC07 reduce small intestinal bacterial overgrowth and hyperammonemia, thereby preventing HE development.

METHODS

The effect of probiotics-Lactobacillus plantarum UBLP40 (10⁷ CFU/day, 14 days) and Bacillus clausii UBBC07 (10⁷ CFU/day, 14 days) combination and standard drug-lactulose (2.5 ml/kg in 3 divided doses, 14 days) was studied in thioacetamide (250 mg/kg for three days) induced acute HE in rats by measuring behavioural parameters, biochemical parameters (serum AST, ALT, ALP and ammonia level), neurochemical parameters and histopathology study in brain and liver.

RESULTS

In contrast to only thioacetamide treated rats, probiotics treatment substantially (p < 0.001) reduced liver function parameters, i.e. serum AST, ALT, ALP, and ammonia, improved behaviour parameters, i.e. decreased motor disruption, improved memory impairment. Probiotics treated rats have also shown a substantial improvement in oxidative stress parameters i.e. reduced lipid peroxidation and increased glutathione level in brain tissue and ameliorated the histopathological changes induced by thioacetamide in the brain and liver.

CONCLUSIONS

It can be concluded based on the findings that the combination therapy of Lactobacillus plantarum UBLP40 and Bacillus clausiiUBBC07 proves to be effective in acute hepatic encephalopathy in the preclinical stage, and further studies are required to assess this therapy potential in the clinical setting.

Chlorogenic acid alleviates thioacetamide-induced toxicity and promotes liver development in zebrafish (Danio rerio) through the Wnt signaling pathway

Chlorogenic acid (CGA) is a phenylpropanoid compound that is well known to improve the antioxidant capacity and other biological activities. However, the roles of CGA in the liver development of organisms are unclear. In the present study, we aimed to investigate the function of CGA in the hepatic development in thioacetamide (TAA)-induced zebrafish embryos. We found that CGA exerted certain beneficial effects on zebrafish larvae from TAA-exposed zebrafish embryos, such as increasing the liver size, body length, heart rate, acetylcholinesterase activity, and motor ability. In addition, CGA displayed an antioxidant effect on TAA-induced zebrafish embryos by enhancing the activities of superoxide dismutase (SOD), catalase (CAT), and glucose-6-phosphate dehydrogenase (G6PDH), and decreasing of the contents of malondialdehyde (MDA), reactive oxygen species (ROS), and nitric oxide (NO). The results of western blotting analysis showed that CGA inhibited cell apoptosis by increasing the levels of Bcl2 apoptosis regulator and decreasing the levels of Bcl2 associated X (Bax), apoptosis regulator and tumor protein P53. Moreover, CGA promoted cell proliferation in TAA-induced zebrafish larvae, as detected using proliferating cell nuclear antigen fluorescence immunostaining. In addition, CGA inhibited the expression of Wnt signaling pathway genes Dkk1 (encoding Dickkopf Wnt signaling pathway inhibitors), and promoted the expression of Lef1 (encoding lymphoid enhancer binding factor 1) and Wnt2bb (encoding wingless-type MMTV integration site family, member 2Bb). When the Wnt signal inhibitor IWR-1 was added, there was no significant change in liver development in the IWR-1 + TAA group compared with the IWR-1 + TAA + CGA group (p <0.05), which suggested that CGA regulates liver development via Wnt signaling pathway. Overall, our results suggested that CGA might alleviate TAA-induced toxicity in zebrafish and promote liver development through the Wnt signaling pathway, which provides a basis for the therapeutic effect of CGA on liver dysplasia.

Tenofovir disoproxil fumarate directly ameliorates liver fibrosis by inducing hepatic stellate cell apoptosis via downregulation of PI3K/Akt/mTOR signaling pathway

Background

Antifibrotic agent for the treatment of liver fibrosis has not been developed so far. Long term treatment of chronic hepatitis B patients with antiviral drugs tenofovir disoproxil fumarate (TDF) and entecavir (ETV) results in the regression of liver fibrosis, but the underlying mechanism has not been clarified. Therefore, we aimed to investigate the direct impact of TDF and ETV on liver fibrosis.

Methods

Activated hepatic stellate cell (HSC) cell lines were used to evaluate the effects of TDF and ETV. After treatment with each antiviral agent, cell viability, morphology, apoptotic features, autophagy and antifibrosis signalling pathways were examined. Then, collagen deposition, fibrosis markers and activated HSCs were measured in liver tissues of the liver fibrosis model mice.

Results

After TDF treatment, the viabilities of LX2 and HSC-T6 cells were decreased, and the cells exhibited apoptotic features, but ETV did not induce these effects. Cleavage of PARP and Caspase-3 and the inhibition of the antiapoptotic gene Bcl-xl indicated activated HSC apoptosis following TDF treatment. TDF simultaneously increased autophagy, which also regulated apoptosis through crosstalk. TDF inactivated the PI3K/Akt/mTOR signalling pathway, which was associated with the activation of both apoptosis and autophagy. In the liver fibrosis mouse model, the fibrotic area and activated HSC markers were decreased by TDF but not ETV treatment. Additionally, apoptotic cells were concentrated in the periportal fibrotic area after TDF treatment, which indicated the specific antifibrotic effect of TDF.

Conclusions

TDF directly ameliorates liver fibrosis by downregulating the PI3K/Akt/mTOR signalling pathway, which results in the apoptosis of activated HSCs. The antifibrotic effects of TDF indicate that it may be a therapeutic agent for the treatment of liver fibrosis.

In vivo hepatoprotective effect of Morinda elliptica stem extract against liver fibrosis induced by thioacetamide

Morinda elliptica L. (Rubiaceae) is a phytomedicinal herb, used to treat gastrointestinal complications in Peninsular Malaysia. The study evaluates the in vivo hepatoprotective activity of ethanolic extract of M. elliptica stem in thioacetamide (TAA) induced liver fibrosis in male Sprague Drawly rats. Thirty adult rats were divided into five groups of six rats each. Rats of the normal control group received intraperitoneal injections (i. p.) of vehicle 10% Tween-20, 5 ml/kg, and hepatotoxic group 200 mg/kg TAA three times per week respectively. Three supplementary groups were treated with TAA plus daily oral silymarin (50 mg/kg) or M. elliptica (250 or 500 mg/kg). After 8 weeks of treatment, all rats were sacrificed. Liver fibrosis was assessed by gross macroscopic and microscopic tissue analysis, histopathological, and biochemical analysis. The livers of the TAA treated group showed uniform coarse granules, hepatocytic necrosis with lymphocytes infiltration. Contrary, the livers of M. elliptica treated groups (250 and 500 mg/kg) were much smoother and the cell damage was much lesser. The livers of M. elliptica treated groups rats showed elevated activity of SOD and CAT with a significant decrease in MDA level at p < .0001. The level of liver damage parameters, that is, ALP, ALT, and AST, bilirubin, total protein, and albumin were restored to the normal comparable to silymarin. M. elliptica stem extract significantly promoted normal rat liver architecture with significant perfections in biochemical parameters. The molecular contents of M. elliptica with hepatoprotective influence could be discovered, is the future prospective of this study.

Toxicity of thioacetamide and protective effects of quercetin in zebrafish (Danio rerio) larvae

Quercetin is a flavonoid compound with a variety of biological properties that is widely distributed throughout the plant kingdom. Studies have found that quercetin has anti-inflammatory, antioxidant, and liver-protective effects, while thioacetamide (TAA) can cause inflammation and liver damage in zebrafish larvae. The purpose of this study was to evaluate whether quercetin can prevent TAA-induced inflammation and liver damage in zebrafish larvae and to investigate the molecular mechanisms involved. Zebrafish Tg transgenic lines were used as the experimental animals. Behavioral, oxidative stress level, proliferative antigen chromogenic antibody, and western blot analyses were carried out on zebrafish larvae in the control group and groups treated with TAA and 12 μM quercetin. The results indicated that quercetin promoted the development of zebrafish larvae damaged by TAA, exhibited antioxidant and anti-inflammatory properties, and promoted cell proliferation. Quercetin reduced the expression of p53 protein in zebrafish larvae injured by TAA, resulting in decreased levels of Bax and increased levels of Bcl-2. The findings suggested quercetin has antiapoptotic action. Quercetin reduced the expression of DKK1 and DKK2 genes related to the Wnt signaling pathway in zebrafish larvae damaged by TAA and increased the expression of Lef1 and wnt2bb. Quercetin may regulate the development of zebrafish larvae damaged by TAA through the Wnt signaling pathway. This study provides the scientific basis for the development and utilization of quercetin and the development of new related drugs.

Captopril suppresses hepatic mammalian target of rapamycin cell signaling and biomarkers of inflammation and oxidative stress in thioacetamide-induced hepatotoxicity in rats

BACKGROUND

The potential inhibitory effects of captopril, the angiotensin-converting enzyme inhibitor, on thioacetamide (TAA)-induced hepatic mammalian target of rapamycin (mTOR), liver injury enzymes, blood pressure, and biomarkers of inflammation and oxidative stress have not been investigated before.

MATERIALS AND METHODS

Rats were either injected with TAA (200 mg/kg; twice a week for 8 weeks) before being sacrificed after 10 weeks (model group) or were pretreated with captopril (150 mg/kg) daily for two weeks prior to TAA injections and continued receiving both agents until the end of the experiment (protective group).

RESULTS

Captopril significantly (p < .05) inhibited TAA-induced hypertension, liver tissue levels of mTOR, TIMP-1, TNF-α, IL-6, MDA; and blood levels of lipids, ALT, and AST. We further demonstrated a significant (p < .01) positive correlation between mTOR scoring and the levels of inflammatory, oxidative and liver injury biomarkers.

CONCLUSIONS

Captopril protects against TAA-induced mTOR, liver injury enzymes, dyslipidemia, hypertension, inflammation, and oxidative stress.

Ashwagandha (Withania somnifera) root extract attenuates hepatic and cognitive deficits in thioacetamide-induced rat model of hepatic encephalopathy via induction of Nrf2/HO-1 and mitigation of NF-κB/MAPK signaling pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Ashwagandha (ASH) is one of the medicinal plants used in traditional Indian, Ayurvedic, and Unani medicines for their broad range of pharmacological activities including, tonic, aphrodisiac, energy stimulant, and counteracting chronic fatigue. Besides, it is used in the treatment of nervous exhaustion, memory-related conditions, insomnia, as well as improving learning ability and memory capacity. ASH is preclinically proven to be efficient in hepatoprotection and improving cognitive impairment, however, its beneficial effects against hepatic encephalopathy (HE) is still unclear. Therefore, this study aimed at investigating the protective effects of ASH root extract against thioacetamide (TAA)-induced HE and delineate the underlying behavioral and pharmacological mechanisms.

MATERIALS AND METHODS

ASH metabolites were identified using UPLC-HRMS. Rats were pretreated with ASH (200 and 400 mg/kg) for 29 days and administrated TAA (i.p, 350 mg/kg) in a single dose. Then, behavioral (open field test, Y-maze, modified elevated plus maze and novel object recognition test), and biochemical (ammonia and hepatic toxicity indices) assessments, as well as oxidative stress markers (MDA and GSH) were evaluated. The hepatic and brain levels of glutamine synthetase (GS), nuclear factor erythroid 2-related factor 2 (Nrf2), heme-oxygenase (HO)-1, inducible nitric oxide synthase (iNOS) were detected by enzyme-linked immunosorbent assay (ELISA). The mRNA expressions of p38/ERK½ were determined using real-time polymerase chain reaction (PCR). Moreover, histopathological investigations and immunohistochemical (NF-κB and TNF-α immunohistochemical expressions) examinations were performed.

RESULTS

Metabolite profiling of ASH revealed more than 45 identified metabolites including phenolic acids, flavonoids and steroidal lactone triterpenoids. Compared to the TAA-intoxicated group, ASH improved the locomotor and cognitive deficits, serum hepatotoxicity indices and ammonia levels, as well as brain and hepatic histopathological alterations. ASH reduced hepatic and brain levels of MDA, GS, and iNOS, and increased their GSH, Nrf2, and HO-1 levels. Also, ASH downregulated p38 and ERK½ mRNA expressions, and NF-κB and TNF-α immunohistochemical expressions in brain and hepatic tissues.

CONCLUSIONS

Our results provided insights into the promising hepato- and neuroprotective effects of ASH, with superiority to 400 mg/kg ASH, to ameliorate HE with its sequential hyperammonemia and liver/brain injuries. This could be attributed to the recorded increase in the spontaneous alternation % and recognition index, antioxidant and anti-inflammatory activities, as well as upregulation of Nrf2 and downregualtion of MAPK signaling pathways.

Schisantherin A ameliorates liver fibrosis through TGF-β1mediated activation of TAK1/MAPK and NF-κB pathways in vitro and in vivo

BACKGROUD

Schisandra chinensis, a traditional Chinese medicine for liver protection, can significantly improve liver fibrosis. However, it is still unclear which active components in Schisandra chinensis play an anti-fibrosis role.

PURPOSE

The purpose of present study was to observe the anti-fibrosis effect of schisantherin A (SCA) on liver fibrosis and explore its underlying mechanism.

METHODS

The liver fibrosis model of mice was constructed by the progressive intraperitoneal injection of thioacetamide (TAA), and SCA (1, 2, and 4 mg/kg) was administered by gavage for 5 weeks. The biochemical indicators and inflammatory cytokines were measured, changes in the pathology of the mice liver were observed by hematoxylin & eosin (H&E) and Masson stainings for studying the anti-fibrosis effect of SCA. A hepatic stellate cell (HSCs) activation model induced by transforming growth factor-β1 (TGF-β1) was established, and the effect of SCA on the HSCs proliferation was observed by MTT assay. The expressions of target proteins related to transforming growth factor-β-activated kinase 1 (TAK1)/mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) pathways were evaluated by western blotting, immunohistochemistry or immunofluorescence analysis, to explore the potential mechanism of SCA.

RESULTS

SCA could significantly ameliorate the pathological changes of liver tissue induced by TAA, and reduce the serum transaminase level, the hydroxyproline level and the expression of α-smooth muscle actin (α-SMA) and collagen 1A1 (COL1A1) proteins in the liver tissue. SCA could significantly lower the levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6) in the serum and liver tissue, and down-regulate the expression of target proteins related to TAK1/MAPK and NF-κB pathways in the liver tissue. The in vitro studies demonstrated that SCA significantly inhibited the proliferation and activation of HCS-T6 cells induced by TGF-β1, decreased TNF-α and IL-6 levels, and inhibited the TAK1 activation induced by TGF-β1 and then the expression of MAPK and NF-κB signaling pathway-related proteins.

CONCLUSION

Together, SCA can ameliorate the liver fibrosis induced by TAA and the HSC-T6 cell activation induced by TGF-β1 in mice, and its mechanism may be to inhibit the HSCs activation and inflammatory response by inhibiting TGF-β1 mediated TAK1/MAPK and signal pathways.

Decreased Expression and Uncoupling of Endothelial Nitric Oxide Synthase in the Cerebral Cortex of Rats with Thioacetamide-Induced Acute Liver Failure

Acute liver failure (ALF) is associated with deregulated nitric oxide (NO) signaling in the brain, which is one of the key molecular abnormalities leading to the neuropsychiatric disorder called hepatic encephalopathy (HE). This study focuses on the effect of ALF on the relatively unexplored endothelial NOS isoform (eNOS). The cerebral prefrontal cortices of rats with thioacetamide (TAA)-induced ALF showed decreased eNOS expression, which resulted in an overall reduction of NOS activity. ALF also decreased the content of the NOS cofactor, tetrahydro-L-biopterin (BH4), and evoked eNOS uncoupling (reduction of the eNOS dimer/monomer ratio). The addition of the NO precursor L-arginine in the absence of BH4 potentiated ROS accumulation, whereas nonspecific NOS inhibitor L-NAME or EDTA attenuated ROS increase. The ALF-induced decrease of eNOS content and its uncoupling concurred with, and was likely causally related to, both increased brain content of reactive oxidative species (ROS) and decreased cerebral cortical blood flow (CBF) in the same model.

Fenugreek seeds attenuate thioacetamide induced liver damage

The intention to conduct this study was to evaluate the hepatoprotective effects of Fenugreek seeds' extract supplementation in thioacetamide induced liver damage in male Sprague Dawley rats. For this study, 24 male Sprague Dawley rats (200-264gm) were distributed randomly into four groups. Group I remained untreated as control rats, group II received thioacetamide (200mg/Kg b.w i.p, administered on alternative days for 8 weeks), group III received thioacetamide (200mg/Kg b.w i.p administered on alternative days for 8 weeks) as well as 2ml of 2% extract of fenugreek seeds (orally administered daily from 4th week till 8th week of the experiment. Group IV only received 2ml of 2% extract of Fenugreek seeds daily for 4 weeks respectively. At the end of the experiment, blood was sampled to obtain plasma that was used for the analysis of liver markers and liver was used for analysis of antioxidant enzymes (catalase and SOD). Increase in total bilirubin, direct bilirubin, ALT and ALP levels, catalase activity and decrease in SOD activity was found in TAA-treated groups which assured liver damage. Whereas, treatment with Fenugreek seeds extract restored the altered levels of total bilirubin, direct bilirubin, ALT, ALP, catalase and SOD activities in the Test + Supp group. The results of this study confirmed the hepatoprotective role of Fenugreek seeds extract in thioacetamide induced liver damage.

Previous liver regeneration induces fibro-protective mechanisms during thioacetamide-induced chronic liver injury

Chronic liver injury is characterised by continuous or repeated epithelial cell loss and inflammation. Hepatic wound healing involves matrix deposition through activated hepatic stellate cells (HSCs) and the expansion of closely associated Ductular Reactions and liver progenitor cells (LPCs), which are thought to give rise to new epithelial cells. In this study, we used the murine thioacetamide (TAA) model to reliably mimic these injury and regeneration dynamics and assess the impact of a recovery phase on subsequent liver injury and fibrosis. Age-matched naïve or 6-week TAA-treated/4-week recovered mice (C57BL/6 J, n = 5-9) were administered TAA for six weeks (C57BL/6 J, n = 5-9). Sera and liver tissues were harvested at key time points to assess liver injury biochemically, by real-time PCR for fibrotic mediators, Sirius Red staining and hydroxyproline assessment for collagen deposition as well as immunofluorescence for inflammatory, HSC and LPC markers. In addition, primary HSCs and the HSC cell line LX-2 were co-cultured with the well-characterised LPC line BMOL and analysed for potential changes in expression of fibrogenic mediators. Our data demonstrate that recovery from a previous TAA insult, with LPCs still present on day 0 of the second treatment, led to a reduced TAA-induced disease progression with less severe fibrosis than in naïve TAA-treated animals. Importantly, primary activated HSCs significantly reduced pro-fibrogenic gene expression when co-cultured with LPCs. Taken together, previous TAA injury established a fibro-protective molecular and cellular microenvironment. Our proof-of principle HSC/LPC co-culture data demonstrate that LPCs communicate with HSCs to regulate fibrogenesis, highlighting a key role for LPCs as regulatory cells during chronic liver disease.

The Ameliorative Effects of Fucoidan in Thioacetaide-Induced Liver Injury in Mice

Liver disorders have been recognized as one major health concern. Fucoidan, a sulfated polysaccharide extracted from the brown seaweed Fucus serratus, has previously been reported as an anti-inflammatory and antioxidant. However, the discovery and validation of its hepatoprotective properties and elucidation of its mechanisms of action are still unknown. The objective of the current study was to investigate the effect and possible modes of action of a treatment of fucoidan against thioacetamide (TAA)-induced liver injury in male C57BL/6 mice by serum biochemical and histological analyses. The mouse model for liver damage was developed by the administration of TAA thrice a week for six weeks. The mice with TAA-induced liver injury were orally administered fucoidan once a day for 42 days. The treated mice showed significantly higher body weights; food intakes; hepatic antioxidative enzymes (catalase, glutathione peroxidase (GPx), and superoxide dismutase (SOD)); and a lower serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and C-reactive protein (CRP) levels. Additionally, a reduced hepatic IL-6 level and a decreased expression of inflammatory-related genes, such as cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS) mRNA was observed. These results demonstrated that fucoidan had a hepatoprotective effect on liver injury through the suppression of the inflammatory responses and acting as an antioxidant. In addition, here, we validated the use of fucoidan against liver disorders with supporting molecular data.

Involvement of neutrophils in rat livers by low-dose thioacetamide administration

The administration with high dose (close to LD50) of thioacetamide (TAA), a hepatotoxicant used widely to induce experimental liver lesions, develops hepatocellular necrosis and subsequent inflammation (mainly M1-/M2-macrophages without neutrophil infiltration) in rats. We analyzed rat livers treated with a low dose TAA (50 mg/kg/body weight) at 6, 12, 18, 24 and 48 hr. The lesions in the affected centrilobular areas consisted of slight hepatocyte degeneration at 12 hr, and inflammatory cell infiltration at 18 and 24 hr; the lesions recovered until 48 hr. Translocation of intranuclei to cytoplasm of HMGB1, a representative molecule of damage-associated molecular patterns, was seen in some hepatocytes mainly at 6, 12, and 18 hr. As an interesting finding, at 12 hr, myeloperoxidase-positive neutrophil infiltration was observed in the affected centrilobular area. Additionally, CD68 M1-/CD163 M2-macrophages increased consistently at 12 to 48 hr. CXCL1, a chemokine for induction of neutrophils, began to increase at 6 hr and gradually increased at 12, 18 and 24 hr, apparently corresponding to the appearance of neutrophils. Collectively, the present findings at the low dose TAA indicated that along with M1-/M2-macrophages, neutrophils were characteristically seen, which might be elicited by cytoplasmic translocation of HMGB1 from nuclei. These finding would be useful for evaluation of hepatotoxicity at the early stages.

Protective role of coffee supplementation in liver cirrhosis: Study in rats

Present study was designed to evaluate the effects of coffee on liver function tests and liver antioxidant enzymes in thioacetamide induced liver cirrhosis in rats. Experimental study period was consisted of eighteen weeks divided into two phases. Therefore 24 rats were distributed randomly into four groups (n=6). Group I served as control. In phase I, group II and III received thioacetamide (200mg/kg body weight intraperitoneally twice a week) and group IV received saline for 12 weeks. In phase II, group II received saline while group III and IV received an oral dose of coffee (0.4mg/Kg b.w) daily for 6 weeks. At the end of the study period rats were sacrificed and blood was collected to get serum and liver was homogenized for the determination of antioxidant enzymes. Marked increase in serum total and direct bilirubin, ALT, AST whereas reduced ALP was observed in test group. The reduced tissue SOD activity and increased tissue catalase and tissue MDA activity were also observed in test group. However, coffee consumption in group III in phase II significantly restored liver biomarkers and the tissue antioxidant enzymes SOD, catalase and MDA activities. In conclusion, thioacetamide induced liver cirrhosis can be prevented by coffee supplementation.

Up-regulation of FUT8 inhibits TGF-β1-induced activation of hepatic stellate cells during liver fibrogenesis

Liver fibrosis is a continuous wound healing response caused by chronic liver injury, and the activation of hepatic stellate cells (HSCs) is considered as the main event for it. Core fucosylation catalyzed by FUT8 refers to adding the fucosyl moiety to the innermost GlcNAc residue of N-linked oligosaccharides and is involved in many biological processes such as cell differentiation, migration, and signaling transduction. Aberrant core fucosylation is associated with a variety of diseases including cardiovascular disease, tumors and neuroinflammation, but much less is understood in liver fibrosis. Herein, we reported FUT8 mRNA level was increased in patients with liver fibrosis from GEO database and positively correlated with fibrosis progression. FUT8 expression and the core fucosylation were also elevated in TAA-induced mouse liver fibrosis model, and were mainly distributed in the fibrous septum of mouse liver. TGF-β1, as the most pro-fibrogenic cytokine, could promote the expression of FUT8 and total core fucosylation levels in HSCs in vitro. However, up-regulation of FUT8 in turn inhibited TGF-β1-induced trans-differentiation, migration and pro-fibrogenic signaling pathways in HSCs. In conclusion, our results suggest that the up-regulation of FUT8 inhibits TGF-β1-induced HSC activation in a negative feedback loop, and provide potential new therapeutic strategy for liver fibrosis by targeting FUT8.