Simvastatin protects against acetaminophen-induced liver injury in mice

Simvastatin-Mediated Nrf2 Activation Induces Fetal Hemoglobin and Antioxidant Enzyme Expression to Ameliorate the Phenotype of Sickle Cell Disease

Sickle cell disease (SCD) is a pathophysiological condition of chronic hemolysis, oxidative stress, and elevated inflammation. The transcription factor Nrf2 is a master regulator of oxidative stress. Here, we report that the FDA-approved oral agent simvastatin, an inhibitor of hydroxymethyl-glutaryl coenzyme A reductase, significantly activates the expression of Nrf2 and antioxidant enzymes. Simvastatin also induces fetal hemoglobin expression in SCD patient primary erythroid progenitors and a transgenic mouse model. Simvastatin alleviates SCD symptoms by decreasing hemoglobin S sickling, oxidative stress, and inflammatory stress in erythroblasts. Particularly, simvastatin increases cellular levels of cystine, the precursor for the biosynthesis of the antioxidant reduced glutathione, and decreases the iron content in SCD mouse spleen and liver tissues. Mechanistic studies suggest that simvastatin suppresses the expression of the critical histone methyltransferase enhancer of zeste homolog 2 to reduce both global and gene-specific histone H3 lysine 27 trimethylation. These chromatin structural changes promote the assembly of transcription complexes to fetal γ-globin and antioxidant gene regulatory regions in an antioxidant response element-dependent manner. In summary, our findings suggest that simvastatin activates fetal hemoglobin and antioxidant protein expression, modulates iron and cystine/reduced glutathione levels to improve the phenotype of SCD, and represents a therapeutic strategy for further development.

The molecular mechanisms of acetaminophen-induced hepatotoxicity and its potential therapeutic targets

Acetaminophen (APAP), a widely used antipyretic and analgesic drug in clinics, is relatively safe at therapeutic doses; however, APAP overdose may lead to fatal acute liver injury. Currently, N-acetylcysteine (NAC) is clinically used as the main antidote for APAP poisoning, but its therapeutic effect remains limited owing to rapid disease progression and the general diagnosis of advanced poisoning. As is well known, APAP-induced hepatotoxicity (AIH) is mainly caused by the toxic metabolite N-acetyl-p-benzoquinone imine (NAPQI), and the toxic mechanisms of AIH are complicated. Several cellular processes are involved in the pathogenesis of AIH, including liver metabolism, mitochondrial oxidative stress and dysfunction, sterile inflammation, endoplasmic reticulum stress, autophagy, and microcirculation dysfunction. Mitochondrial oxidative stress and dysfunction are the major cellular events associated with APAP-induced liver injury. Many biomolecules involved in these biological processes are potential therapeutic targets for AIH. Therefore, there is an urgent need to comprehensively clarify the molecular mechanisms underlying AIH and to explore novel therapeutic strategies. This review summarizes the various cellular events involved in AIH and discusses their potential therapeutic targets, with the aim of providing new ideas for the treatment of AIH.

Hepatocyte Specific gp130 Signalling Underlies APAP Induced Liver Injury

N-acetyl-p-aminophenol (APAP)-induced liver damage is associated with upregulation of Interleukin-11 (IL11), which is thought to stimulate IL6ST (gp130)-mediated STAT3 activity in hepatocytes, as a compensatory response. However, recent studies have found IL11/IL11RA/gp130 signaling to be hepatotoxic. To investigate further the role of IL11 and gp130 in APAP liver injury, we generated two new mouse strains with conditional knockout (CKO) of either Il11 (CKO^Il11) or gp130 (CKO^gp130) in adult hepatocytes. Following APAP, as compared to controls, CKO^gp130 mice had lesser liver damage with lower serum Alanine Transaminase (ALT) and Aspartate Aminotransferase (AST), greatly reduced serum IL11 levels (90% lower), and lesser centrilobular necrosis. Livers from APAP-injured CKO^gp130 mice had lesser ERK, JNK, NOX4 activation and increased markers of regeneration (PCNA, Cyclin D1, Ki67). Experiments were repeated in CKO^Il11 mice that, as compared to wild-type mice, had lower APAP-induced ALT/AST, reduced centrilobular necrosis and undetectable IL11 in serum. As seen with CKO^gp130 mice, APAP-treated CKO^Il11 mice had lesser ERK/JNK/NOX4 activation and greater features of regeneration. Both CKO^gp130 and CKO^Il11 mice had normal APAP metabolism. After APAP, CKO^gp130 and CKO^Il11 mice had reduced Il6, Ccl2, Ccl5, Il1β, and Tnfα expression. These studies exclude IL11 upregulation as compensatory and establish autocrine, self-amplifying, gp130-dependent IL11 secretion from damaged hepatocytes as toxic and anti-regenerative.

Simvastatin Improves Microcirculatory Function in Nonalcoholic Fatty Liver Disease and Downregulates Oxidative and ALE-RAGE Stress

Increased reactive oxidative stress, lipid peroxidation, inflammation, and fibrosis, which contribute to tissue damage and development and progression of nonalcoholic liver disease (NAFLD), play important roles in microcirculatory disorders. We investigated the effect of the modulatory properties of simvastatin (SV) on the liver and adipose tissue microcirculation as well as metabolic and oxidative stress parameters, including the advanced lipoxidation end product–receptors of advanced glycation end products (ALE-RAGE) pathway. SV was administered to an NAFLD model constructed using a high-fat–high-carbohydrate diet (HFHC). HFHC caused metabolic changes indicative of nonalcoholic steatohepatitis; treatment with SV protected the mice from developing NAFLD. SV prevented microcirculatory dysfunction in HFHC-fed mice, as evidenced by decreased leukocyte recruitment to hepatic and fat microcirculation, decreased hepatic stellate cell activation, and improved hepatic capillary network architecture and density. SV restored basal microvascular blood flow in the liver and adipose tissue and restored the endothelium-dependent vasodilatory response of adipose tissue to acetylcholine. SV treatment restored antioxidant enzyme activity and decreased lipid peroxidation, ALE-RAGE pathway activation, steatosis, fibrosis, and inflammatory parameters. Thus, SV may improve microcirculatory function in NAFLD by downregulating oxidative and ALE-RAGE stress and improving steatosis, fibrosis, and inflammatory parameters.

Modulation of HMGB1 Release in APAP-Induced Liver Injury: A Possible Strategy of Chikusetsusaponin V Targeting NETs Formation

Acetaminophen (APAP), one of the most common antipyretic analgesics, which is safe at therapeutic dose, cause acute liver injury and even death at overdose. However, the mechanism of APAP-induced inflammation in liver injury is still controversial. Therefore, effective drug intervention is urgently needed. The aim of this study was to explore the inflammatory exact mechanism of APAP, especially on neutrophils, and to study the intervention effect of Chikusetsusaponin V (CKV) derived from Panax japonicus. Establishment of hepatotoxicity model of APAP in vitro and in vivo. In vitro, HepG2 cells, AML12 cells, primary mouse hepatocytes and neutrophils were used to mimic APAP-affected hepatocytes and neutrophil. In vivo, C57BL/6 mice were administrated overdose of APAP with or without neutrophil depletion or abolishing neutrophil extracellular traps (NETs) formation. In this study, APAP stimulation increased the level of HMGB1, IL-1β and Caspase-1 in mouse liver, especially hepatocytes, which had a synergistic effect with LPS/ATP combination. NETs were formatted at early stage of APAP or HMGB1-stimulated neutrophils’ damage. Conditioned mediums from APAP-treated hepatocytes induced more significant NETs than direct APAP stimulation. Neutrophil depletion or abolishing NETs formation decreased HMGB1 level, eventually blocked hepatocytes necrosis. CKV pretreatment interfered Caspase-1 activation and HMGB1 release in APAP-damaged hepatocytes. CKV also prevented NETs formation. These results indicate that the production of HMGB1 may depend on the activation of Caspase-1 and play a key role in liver inflammation caused by APAP. The cross-dialogue between hepatocytes and neutrophils can be mediated by HMGB1. Therefore, CKV has a positive intervention effect on NETs-related inflammation in APAP-damaged liver, targeting Caspase-1-HMGB1.

DHA-enriched phospholipids from large yellow croaker roe regulate lipid metabolic disorders and gut microbiota imbalance in SD rats with a high-fat diet

Large yellow croaker roe phospholipids (LYCRPLs) have great nutritional value because they are rich in docosahexaenoic acid (DHA), which is an n-3 polyunsaturated fatty acid (n-3 PUFA). In previous research, we studied the effect of LYCRPLs on the inhibition of triglyceride accumulation at the cellular level. However, its lipid regulation effect in rats on a high-fat diet and its influence on the gut microbiota has not yet been clarified. In this study, a high-fat diet was used to induce the lipid metabolism disorder in SD rats, and simvastatin, low-dose, medium-dose and high-dose LYCRPLs were given by intragastric administration for 8 weeks. The rats' body weight, food intake, organ index, blood biochemical indicators, epididymal fat tissue and liver histopathology were compared and analyzed. High-throughput 16S rRNA gene sequencing technology and bioinformatics analysis technology were also used to analyze the diversity of gut microbiota in rats. We found that LYCRPLs can significantly regulate lipid metabolism, and improve the gut microbiota disorder induced in rats by a high-fat diet. These results can lay a foundation for the study of the regulation mechanism of LYCRPLs lipid metabolism, and also provide a theoretical basis for the development of LYCRPLs as functional food additives and excipients with hypolipidemic effects.

Acetaminophen-induced renal toxicity: preventive effect of silver nanoparticles

Present study was planned to investigate the ameliorative effect of silver nanoparticles (AgNPs) on acetaminophen-induced nephrotoxicity. Our results demonstrate that therapy of AgNPs at three different doses (50, 100 and 150 μg/kg once only) prevented the acetaminophen (2 g/kg once only) induced acute renal toxicity. AgNPs treated animals also show less intensity in the histological alterations in kidneys and corroborating the results of analysis of serum urea and creatinine. In addition, AgNPs therapy prevented the acetaminophen-induced oxidative stress, which was confirmed by the alleviated lipid peroxidation, enhanced renal reduced glutathione content and restored enzymatic activities of superoxide dismutase, catalase and adenosine triphosphatase in kidney. Thus, our results demonstrate a possible protective potential of AgNPs on renal toxicity induced by acetaminophen. This study will definitely lead to the development of therapeutic drug against nephrotoxicity, after further clinical and preclinical studies.

Hepatoprotective effect of Centella asiatica 50% ethanol extract against acetaminophen-induced acute liver injury in BALB/c mice

N-acetyl-p-aminophenol (acetaminophen, APAP) is a well-known component of analgesic and antipyretic monotherapy products. However, exceeding the recommended dose can lead to serious injury to the liver. We conducted this study to determine the potential of Centella asiatica as a natural substance to protect against APAP-induced liver injury. When acute hepatotoxicity was induced in mice by APAP overdose, their liver weight decreased significantly (p < 0.05). However, mice treated with C. asiatica 50% ethanol extract (CA-HE50, 200 mg/kg) for a week before induction of hepatotoxicity by APAP had similar liver weights to those of mice in which hepatotoxicity was not induced. In particular, levels of aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase, which are biomarkers of liver injury, were significantly increased by APAP and dose-dependently decreased by CA-HE50 (p < 0.05). Glutathione and malondialdehyde, indicators of oxidative stress, were significantly changed by APAP and CA-HE50 (p < 0.05). In addition, hepatic necrosis and expression of genes encoding pro-inflammatory cytokines (tumor necrosis factor-α, interleukin (IL)-1β, and IL-4) induced by APAP were inhibited by CA-HE50, and these results were dose-dependent. Through our in vivo studies, we found that CA-HE50 can help prevent APAP-induced hepatic tissue injury in BALB/c mice. Furthermore, CA-HE50 was effective at protecting RAW 264.7 cells from lipopolysaccharide-induced cytotoxicity and inhibiting the release of nitric oxide from these cells; in particular, asiaticoside was found to be a key component of CA-HE50 responsible for these effects. Therefore, we suggest that CA-HE50 has potential applications in functional health foods and drugs.

Improvement of therapeutic potential N-acetylcysteine in acetaminophen hepatotoxicity by encapsulation in PEGylated nano-niosomes

AIMS

N-Acetylcysteine (NAC) is an effective antidote for the treatment of acetaminophen (APAP) poisoning; however, due to its low stability and bioavailability, repeated dosing of NAC is needed. This study investigated the therapeutic efficacy of NAC by niosomal carriers.

MATERIALS AND METHODS

Niosomes were synthesized using surface active agents film hydration method and their physicochemical properties were characterized. In the in vivo study, in addition to control group, male rats were divided in different groups and challenged with an oral dose of APAP (2000 mg/kg); 4 h later, rats were administered normal saline, empty niosome (NIO), NAC (25 mg/kg) and NAC-loaded niosome (NAC-NIO) respectively, and sacrificed 48 h post-APAP overdose.

KEY FINDINGS

The particle size and zeta potential of NAC-NIO were 242.3 ± 18.5 nm and -23.9 ± 1.6 mV. The loading and encapsulation efficiency of niosomes were 1.22% ± 0.02% and 26.76% ± 6.02%. APAP administration leads to hepatic damage as evidenced by increases in serum hepatic enzyme levels and tissue levels of nitric oxide and lipid peroxidation as well as decreases in hepatic levels of reduced glutathione, catalase, superoxide dismutase, and glutathione peroxidase. Treatment of rats with NIO-NAC was remarkably more effective than NAC in improving biochemical changes such as serum hepatic aminotransferases. These findings were correlated well to the histopathological experiments.

SIGNIFICANCE

Our results suggest that NAC when delivered as a niosomal structure, is potentially more effective than NAC standard, in improving APAP-induced hepatotoxicity.

The PI3K/Akt and NF-κB signaling pathways are involved in the protective effects of Lithocarpus polystachyus (sweet tea) on APAP-induced oxidative stress injury in mice

Acetaminophen (APAP)-induced acute liver injury (ALI) is a health issue that has gradually attracted attention, and is often regarded as a model of drug-induced hepatotoxicity. The leaves of Lithocarpus polystachyus Rehd. (named as “sweet tea”, ST) usually serve as tea drink and folk medicine for healthcare in the southwest part of China. In previous reports, it has been proven to protect various animal models, except for APAP-induced liver injury model. Therefore, this study initially explored the protective effect of ST leaf extract (STL-E) on hepatotoxicity induced by APAP in ICR mice. STL-E of 50 and 100 mg kg⁻¹ were given to each group for 7 days. ALI was intraperitoneally induced by APAP treatment (i.p. 250 mg per kg body weight). Biochemical markers, levels of inflammatory factors, histopathological staining and western blotting were used to analyze the inflammation and apoptosis of liver tissues. Interestingly, the treatment with STL-E significantly attenuated APAP-induced liver injury (p < 0.05). Moreover, STL-E partially mitigated APAP-induced liver injury by effectively activating the PI3K/Akt pathway and inhibiting the NF-κB pathway. In a word, STL-E protected liver against APAP-induced hepatotoxicity by inhibiting the PI3K/Akt-mediated apoptosis signal pathway and inhibiting the NF-κB-mediated signaling pathway.

Acetaminophen (APAP)-induced acute liver injury (ALI) is a health issue that has gradually attracted attention, and is often regarded as a model of drug-induced hepatotoxicity.

Hepatoprotective Effect of Baicalein Against Acetaminophen-Induced Acute Liver Injury in Mice

Baicalein (BAI), one of the main components of Scutellaria baicalensis Georgi, possesses numerous pharmacological properties, including anti-cancer, anti-oxidative, anti-virus and anti-bacterial activities. The purpose of this study was to evaluate the hepatoprotective effect of baicalein against acetaminophen (APAP)-exposed liver injury in mice, and elucidate the underlying hepatoprotective mechanism. Baicalein pretreatment significantly alleviated the elevation of IL-6, IL-1β and TNF-α in serum and hepatic in a dose-dependent manner. It also dose-dependently reduced the hepatic malondialdehyde (MDA) concentration, as well as the depletion of hepatic superoxide dismutase (SOD), hepatic glutathione (GSH) and hepatic catalase (CAT). Moreover, pretreatment with baicalein significantly ameliorated APAP-exposed liver damage and histological hepatocyte changes. Baicalein also relieved APAP-induced autophagy by regulating AKT/mTOR pathway, LC3B and P62 expression. Furthermore, the hepatoprotective effect of baicalein to APAP-induced liver injury involved in Jak2/Stat3 and MAPK signaling pathway. Taken together, our findings suggested that baicalein exhibits the ability to prevent liver from APAP-induced liver injury and provided an underlying molecular basis for potential applications of baicalein to cure liver injuries.

Hepatoprotective Effect of Ugonin M, A Helminthostachyszeylanica Constituent, on Acetaminophen-Induced Acute Liver Injury in Mice

The present study aimed to discover the possible effectiveness of Ugonin M, a unique flavonoid isolated from Helminthostachys zeylanica-a traditional Chinese medicine used as anti-inflammatory medicine-and to elucidate the potential mechanisms of Ugonin M in the acute liver injury induced by acetaminophen (APAP). In this study, Ugonin M significantly ameliorated APAP-induced histopathological changes and the typical liver function biomarkers (i.e., alanine aminotransferase (ALT), aspartate aminotransferase (AST), and total bilirubin (T-Bil)). It also affected APAP-induced abnormal lipid metabolism including total cholesterol (TC) and triglyceride (TG) in the serum. In inflammatory pharmacological action, Ugonin M suppressed the pro-inflammatory mediators such as nitric oxide (NO) and the lipid peroxidation indicator malondialdehyde (MDA). In addition, Ugonin M reinforced hemeoxygenase-1 (HO-1) protein expression and the production of antioxidant enzymes viz superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT). Furthermore, inflammation-associated cytokines including tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and IL-1β as well as proteins such as inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) were decreased by the pretreatment of Ugonin M. Moreover, this study found that pretreatment of Ugonin M apparently decreased nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinases (MAPKs) activation via inhibition of the degradation of NF-κB, inhibitory κB-α (IκB-α), extracellular regulated kinase (ERK), c-Jun-N-terminal (JNK), and p38 active phosphorylation. In conclusion, Ugonin M significantly showed a protective effect against APAP-induced liver injury by reducing oxidative stress and inflammation. Thus, Ugonin M could be one of the effective components of H. zeylanica that plays a major role in the treatment of inflammatory disorders.

Polydatin protects against acetaminophen-induced hepatotoxicity in mice via anti-oxidative and anti-apoptotic activities

Polydatin protects against acetaminophen-induced hepatotoxicity in mice.