Dimethyl fumarate protects thioacetamide-induced liver damage in rats: Studies on Nrf2, NLRP3, and NF-κB

Intrinsic diving reflex induces potent antioxidative response by activation of NRF2 signaling

Aims

This study aims to elucidate the underlying mechanisms of diving reflex, a powerful endogenous mechanism supporting underwater mammalian survival. Antioxidative responses, observed in marine mammals, may be contributing factors. Using a multi-organ approach, this study assesses whether acute and chronic diving reflex activate nuclear factor-erythroid-2-related factor 2 (NRF2) signaling pathways, which regulate cellular antioxidant responses.

Methods

Male Sprague-Dawley rats ( n =38) underwent either a single diving session to elicit acute diving reflex, or daily diving sessions for 4-weeks to produce chronic diving reflex. NRF2 (total, nuclear, phosphorylated), NRF2-downstream genes, and malondialdehyde were assessed via Western blot, immunofluorescence, RT-PCR, and ELISA in brain, lung, kidney, and serum.

Results

Diving reflex increased nuclear NRF2, phosphorylated NRF2, and antioxidative gene expression, in an organ-specific and exposure time-specific manner. Comparing organs, the brain had the highest increase of phosphorylated NRF2 expression, while kidney had the highest degree of nuclear NRF2 expression. Comparing acute and chronic sessions, phosphorylated NRF2 increased the most with chronic diving reflex, but acute diving reflex had the highest antioxidative gene expression. Notably, calcitonin gene-related peptide appears to mediate diving reflex' effects on NRF2 activation.

Conclusions

Acute and chronic diving reflex activate potent NRF2 signaling in the brain and peripheral organs. Interestingly, acute diving reflex induces higher expression of downstream antioxidative genes compared to chronic diving reflex. This result contradicts previous assumptions requiring chronic exposure to diving for induction of antioxidative effects and implies that the diving reflex has a strong translational potential during preconditioning and postconditioning therapies.

Key Points

Diving reflex activates potent NRF2 signaling via multiple mechanisms, including phosphorylation, nuclear translocation, and KEAP1 downregulation with both acute and chronic exposure.Diving reflex activates NRF2 via differential pathways in the brain and other organs; phosphorylated NRF2 increases more in the brain, while nuclear NRF2 increases more in the peripheral organs.Acute diving reflex exposure induces a more pronounced antioxidative effect than chronic diving reflex exposure, indicating that the antioxidative response activated by diving reflex is not dependent upon chronic adaptive responses and supports diving reflex as both a preconditioning and postconditioning treatment.

Protective role of eugenol against diabetes-induced oxidative stress, DNA damage, and apoptosis in rat testes

Diabetes mellitus, a metabolic disorder alters gonadal development and spermatogenesis, reactive oxygen species production, DNA damage, and apoptosis, which subsequently lead to male subfertility. Eugenol is an antioxidant, traditionally used as medication for digestive disorders and antioxidant therapy, decrease transport of glucose from GIT to systemic circulation. This experiment was aimed to decipher cellular and molecular insights of eugenol in protecting diabetic germ cells in rats. Rats were assigned randomly into five groups: control, eugenol control (Eugenol 400; EUG), diabetic (DIA), diabetic + eugenol 100 (DIA + EUG 100), and diabetic + eugenol 400 (DIA + EUG 400). EUG 400 and DIA + EUG 400 groups received 400 mg/kg eugenol orally. DIA + EUG 100 group received 100 mg/kg eugenol. Treatment was conducted for 4 weeks. Type 1 diabetes was induced by injecting a single i.p. dose of streptozotocin (55 mg/kg). Morphometric, biochemical, sperm parameters, oxidative stress, hormonal levels, histopathology, and fibrosis in the testis and epididymis, were evaluated. DNA damage was evaluated using halo and comet assays; DNA fragmentation and apoptosis using TUNEL assay. Eugenol treatment significantly normalized biochemical parameters, reduced MDA while increased albumin and GSH levels in diabetes. Eugenol significantly increased sperm numbers, motility and attenuated abnormal sperm head morphology in diabetes. Moreover, eugenol significantly reversed diabetes-induced cellular damages, altered spermatogenesis, and collagen deposition in testis and epididymis. It also significantly attenuated diabetes-associated DNA breaks and apoptosis. These findings suggest that 4 weeks treatment with 400 mg/kg of eugenol could be beneficial for diabetic patients to prevent subfertility.

Unveiling thioacetamide-induced toxicity: Multi-organ damage and omitted bone toxicity

Thioacetamide (TAA), a widely employed hepatotoxic substance, has gained significant traction in the induction of liver failure disease models. Upon administration of TAA to experimental animals, the production of potent oxidative derivatives ensues, culminating in the activation of oxidative stress and subsequent infliction of severe damage upon multiple organs via dissemination through the bloodstream. This review summarized the various organ damages and corresponding mechanistic explanations observed in previous studies using TAA in toxicological animal experiments. The principal pathological consequences arising from TAA exposure encompass oxidative stress, inflammation, lipid peroxidation, fibrosis, apoptosis induction, DNA damage, and osteoclast formation. Recent in vivo and in vitro studies on TAA bone toxicity have confirmed that long-term high-dose use of TAA not only induces liver damage in experimental animals but also accompanies bone damage, which was neglected for a long time. By using TAA to model diseases in experimental animals and controlling TAA dosage, duration of use, and animal exposure environment, we can induce various organ injury models. It should be noted that TAA-induced injuries have a time-dependent effect. Finally, in our daily lives, especially for researchers, we should take precautions to minimize TAA exposure and reduce the probability of related organ injuries.

Simultaneous intervention against oxidative stress and inflammation by targeting Nrf2/ARE and NLRP3 inflammasome pathway mitigates thioacetamide-induced liver fibrosis in rat

Liver fibrosis is a typical pathological state/stage involved in most chronic liver diseases and its persistence results in cirrhosis. Inflammasomes are cytoplasmic sensors that induce inflammation in response to stress. Glibenclamide (GLB) is an USFDA-approved drug for type 2 diabetes and is reported to possess anti-inflammatory activity by inhibiting inflammatory cytokines. Dimethyl fumarate (DMF) is an USFDA-approved drug for multiple sclerosis and has been reported to activate the Nrf2/ARE pathway to maintain the cellular antioxidant balance. A total of 36 rats were randomized into six groups (n = 6 each). The rats were injected with thioacetamide (TAA) 200 mg/kg, intraperitoneally every third day for eight consecutive weeks to induce liver fibrosis and oral treatment of GLB 0.5 mg/kg/day and DMF 25 mg/kg/day, and their combinations were provided for the last four consecutive weeks. Treatment with GLB, DMF, and GLB+DMF significantly protected against TAA-mediated oxidative stress and inflammatory conditions by improving hepatic function test, triglycerides, hydroxyproline, and histopathological alterations, by inhibiting the NLRP3 inflammasome signaling and fibrogenic markers, and by activating Nrf2/ARE pathway in Wistar rats. The present results suggest that simultaneous Nrf2/ARE activation and NLRP3 inflammasome inhibition could significantly contribute to developing a novel therapy for patients with liver fibrosis.

GAS5-inhibited hepatocyte pyroptosis contributes to hepatic stellate cell inactivation via microRNA-684 and AHR

Hepatocyte pyroptosis has been shown to be involved in liver damage progression. Previously, we found that growth arrest-specific 5 (GAS5) is a regulator of hepatic stellate cell (HSC) activation. However, whether GAS5 plays a role in hepatocyte pyroptosis remains unclear. In this study, reduced GAS5 was shown in CCl₄-treated mice and restoration of GAS5-inhibited liver fibrosis in vivo. Hepatocyte pyroptosis participated in the effects of GAS5-inhibited liver fibrosis, associated with reduced caspase-1, NLRP3, and IL-1β (hepatocyte pyroptosis markers). Notably, AHR expression, a suppressor of NLRP3, was enhanced by GAS5. Silencing AHR inhibited GAS5-mediated hepatocyte pyroptosis. GAS5 and AHR were targets of microRNA-684 (miR-684). In addition, the effects of GAS5 on hepatocyte pyroptosis could be inhibited by miR-684. Interestingly, GAS5-mediated hepatocyte pyroptosis contributed to HSC inactivation. In conclusion, we demonstrate that GAS5 inhibits hepatocyte pyroptosis and HSC activation, at least in part, via regulation of miR-684 and AHR.

SIRT1/Nrf2/NF-κB Signaling Mediates Anti-Inflammatory and Anti-Apoptotic Activities of Oleanolic Acid in a Mouse Model of Acute Hepatorenal Damage

Background and objectives: Oleanolic acid (OA) is a penta-cyclic triterpene with diverse bioactivities such as anticarcinogenic, antiviral, antimicrobial, hepatoprotective, anti-atherosclerotic, hypolipidemic, and gastroprotective. However, its effects on hepatorenal damage remain unclear. The protective activity of OA, separated from Viscum schimperi (Loranthaceae), against TAA (thioacetamide)-produced acute hepatic and renal damage was explored. Materials and Methods: Mice were treated with OA for 7 days before TAA (200 mg/kg, i.p.). Serum indices of hepatorenal injury, pathological lesions, molecular biological indexes, and inflammatory/apoptotic genes were estimated. Results: The tissues of both organs were greatly affected by the TAA injection. That was evident through increased serum markers of hepato-renal injury as well as remarkable histopathological lesions. TAA-induced injury was associated with oxidative and inflammatory responses in both organs as there was an elevation of oxidative stress parameters (4-HNE (4-hydroxy-nonenal), MDA (malondialdehyde), NOx (nitric oxide)), decline of antioxidants (reduced glutathione (GSH), superoxide dismutase (SOD), and total antioxidant capacity (TAC)), and an increase in the gene expression/level of inflammatory mediators (interleukins (1β&6)). The inflammatory response was linked to a significant activation of NF-κB (nuclear-factor kappa-B)/TNF-α (tumor-necrosis factor-alpha) signaling. The inflammatory response in both organs was accompanied by apoptotic changes, including a rise in the gene expression and level of apoptotic parameters (caspase-3 and Bax) along with a decline in Bcl-2 (anti-apoptotic parameter) gene expression and level. These pathogenic events were found to be closely related to the suppression of the antioxidant signaling pathway, Nrf2 (nuclear-factor erythroid 2-related factor-2)/SIRT1 (sirtuin-1)/HO-1 (heme-oxygenase 1). On the other hand, OA significantly ameliorated TAA-induced injury in both organs. On the other hand, OA counterpoised the inflammatory response as it ameliorated NF-κB/TNF-α signaling and cytokine release. OA enhanced Nrf2/SIRT1/HO-1 signaling and counteracted apoptotic damage. Conclusions: OA showed anti-inflammation and antiapoptotic capacities that effectively suppressed TAA-induced acute hepatorenal damage.

Neuromodulatory role of L-arginine: nitric oxide precursor against thioacetamide-induced-hepatic encephalopathy in rats via downregulation of NF-κB-mediated apoptosis

The aim of the present study was to investigate the impact of arginine (ARG), a nitric oxide (NO) precursor, on thioacetamide (TAA)-induced hepatic encephalopathy (HE) in rats by injection of TAA (100 mg/kg, i.p) three times per week for six consecutive weeks. TAA-injected rats were administered ARG (100 mg/kg; p.o.) concurrently with TAA for the six consecutive weeks. Blood samples were withdrawn, and rats were sacrificed; liver and brain tissues were isolated. Results of the present study demonstrated that ARG administration to TAA-injected rats revealed a restoration in the serum and brain ammonia levels as well as serum aspartate transaminase, alanine transaminase, and alkaline phosphatase and total bilirubin levels as well as behavioral alterations evidenced by restoration in locomotor activity, motor skill performance, and memory impairment. ARG showed also improvement in the hepatic and neuro-biochemical values, pro-inflammatory cytokines, and oxidative stress biomarkers. All these results were confirmed by histopathological evaluation as well as ultrastructural imaging of the cerebellum using a transmission electron microscope. Furthermore, treatment with ARG could ameliorate the immunological reactivity of nuclear factor erythroid-2-related factor 2 (Nrf2) and cleaved caspase-3 proteins in the cerebellum and hepatic tissues. From all the previous results, it can be fulfilled that ARG showed a beneficial role in modulating the adverse complications associated with TAA-induced HE in rats via reducing hyperammonemia and downregulating nuclear factor kappa B (NF-κB)-mediated apoptosis.

Psoriatic disease and non-alcoholic fatty liver disease shared pathogenesis review

Psoriatic disease (PD) and non-alcoholic fatty liver disease (NAFLD) potentially share disease pathways given the numerous inflammatory pathways involved in both diseases and a higher prevalence of NAFLD in PD patients.  Metabolic syndrome and obesity are a key link between the two diseases, but even when controlling for this, associations between both diseases are still seen. Therapeutics that impact metabolic or inflammatory pathways may be impactful in both PD and NAFLD. In this review, we describe common inflammatory pathways contributing to both PD and NAFLD and critically review the potential impact of treatments for and on both diseases.

CD44-Targeting Drug Delivery System of Exosomes Loading Forsythiaside A Combats Liver Fibrosis via Regulating NLRP3-Mediated Pyroptosis

Liver fibrosis is a progressive pathological process induced by various stimuli and may progress to liver cirrhosis and cancer. Forsythiaside A (FA) is an active ingredient extracted from traditional Chinese medicine Forsythiae Fructus and has prominent hepatoprotective activities. However, the unsatisfactory pharmacokinetic properties restrict its clinical application. In this study, the nanocarrier of CD44-specific ligand Hyaluronic acid (HA)-modified milk-derived exosomes (mExo) encapsulated with FA (HA-mExo-FA) is developed. As a result, HA modification could deliver drug-loaded exosomes to the target cells and form a specific ligand-receptor interaction with CD44, thus improving the anti-liver fibrosis effect of FA. In vitro findings indicate that HA-mExo-FA could inhibit TGF-β1-induced LX2 cell proliferation, reduce α-SMA and collagen gene and protein levels, and promote the apoptosis of activated LX2 cells. In vivo results demonstrate that HA-mExo-FA could improve liver morphology and function changes in zebrafish larvae. The anti-liver fibrosis mechanism of HA-mExo-FA may be attributed to the inhibition of NLRP3-mediated pyroptosis. In addition, the effect of HA-mExo-FA on TAA-induced increase in NLRP3 production is attenuated by NLRP3 inhibitor MCC950. Collectively, this study demonstrates the promising application of HA-mExo-FA in drug delivery with high specificity and provides a powerful and novel delivery platform for liver fibrosis therapy.

Ameliorative Effect of Chitosan Oligosaccharides on Hepatic Encephalopathy by Reshaping Gut Microbiota and Gut-Liver Axis

This study investigated the influence of chitosan oligosaccharides (COSs) on a thioacetamide-induced hepatic encephalopathy (HE) Wistar rat model. COS treatment statistically reduced the false neurotransmitters and blood ammonia in HE rats, along with the suppression of oxidative stress and inflammation. The disbalanced gut microbiota was detected in HE rats by 16S rDNA sequencing, but the abundance alterations of some intestinal bacteria at either the phylum or genus level were at least partly restored by COS treatment. According to metabolomics analysis of rat feces, six metabolism pathways with the greatest response to HE were screened, several of which were remarkably reversed by COS. The altered metabolites might serve as a bridge for the alleviated HE rats treated with COS and the enhanced intestinal bacterial structure. This study provides novel guidance to develop novel food or dietary supplements to improve HE diseases due to the potential beneficial effect of COS on gut-liver axis.

Gut microbiota–mitochondrial inter-talk in non-alcoholic fatty liver disease

The increasing prevalence of non-alcoholic fatty liver disease (NAFLD), which is a progressive disease, has exerted huge a healthcare burden worldwide. New investigations have suggested that the gut microbiota closely participates in the progression of NAFLD through the gut–liver axis or gut–brain–liver axis. The composition of the microbiota can be altered by multiple factors, primarily dietary style, nutritional supplements, or exercise. Recent evidence has revealed that gut microbiota is involved in mitochondrial biogenesis and energy metabolism in the liver by regulating crucial transcription factors, enzymes, or genes. Moreover, microbiota metabolites can also affect mitochondrial oxidative stress function and swallow formation, subsequently controlling the inflammatory response and regulating the levels of inflammatory cytokines, which are the predominant regulators of NAFLD. This review focuses on the changes in the composition of the gut microbiota and metabolites as well as the cross-talk between gut microbiota and mitochondrial function. We thus aim to comprehensively explore the potential mechanisms of gut microbiota in NAFLD and potential therapeutic strategies targeting NAFLD management.

Transcriptomic Analysis of Fumarate Compounds Identifies Unique Effects of Isosorbide Di-(Methyl Fumarate) on NRF2, NF-kappaB and IRF1 Pathway Genes

Dimethyl fumarate (DMF) has emerged as a first-line therapy for relapsing-remitting multiple sclerosis (RRMS). This treatment, however, has been limited by adverse effects, which has prompted development of novel derivatives with improved tolerability. We compared the effects of fumarates on gene expression in astrocytes. Our analysis included diroximel fumarate (DRF) and its metabolite monomethyl fumarate (MMF), along with a novel compound isosorbide di-(methyl fumarate) (IDMF). Treatment with IDMF resulted in the largest number of differentially expressed genes. The effects of DRF and MMF were consistent with NRF2 activation and NF-κB inhibition, respectively. IDMF responses, however, were concordant with both NRF2 activation and NF-κB inhibition, and we confirmed IDMF-mediated NF-κB inhibition using a reporter assay. IDMF also down-regulated IRF1 expression and IDMF-decreased gene promoters were enriched with IRF1 recognition sequences. Genes altered by each fumarate overlapped significantly with those near loci from MS genetic association studies, but IDMF had the strongest overall effect on MS-associated genes. These results show that next-generation fumarates, such as DRF and IDMF, have effects differing from those of the MMF metabolite. Our findings support a model in which IDMF attenuates oxidative stress via NRF2 activation, with suppression of NF-κB and IRF1 contributing to mitigation of inflammation and pyroptosis.

The Nrf2 Pathway in Liver Diseases

Oxidative stress is the leading cause of most liver diseases, such as drug-induced liver injury, viral hepatitis, and alcoholic hepatitis caused by drugs, viruses, and ethanol. The Kelch-like ECH-associated protein 1-NFE2-related factor 2 (Keap1-Nrf2) system is a critical defense mechanism of cells and organisms in response to oxidative stress. Accelerating studies have clarified that the Keap1-Nrf2 axis are involved in the prevention and attenuation of liver injury. Nrf2 up-regulation could alleviate drug-induced liver injury in mice. Moreover, many natural Nrf2 activators can regulate lipid metabolism and oxidative stress of liver cells to alleviate fatty liver disease in mice. In virus hepatitis, the increased Nrf2 can inhibit hepatitis C viral replication by up-regulating hemeoxygenase-1. In autoimmune liver diseases, the increased Nrf2 is essential for mice to resist liver injury. In liver cirrhosis, the enhanced Nrf2 reduces the activation of hepatic stellate cells by reducing reactive oxygen species levels to prevent liver fibrosis. Nrf2 plays a dual function in liver cancer progression. At present, a Nrf2 agonist has received clinical approval. Therefore, activating the Nrf2 pathway to induce the expression of cytoprotective genes is a potential option for treating liver diseases. In this review, we comprehensively summarized the relationships between oxidative stress and liver injury, and the critical role of the Nrf2 pathway in multiple liver diseases.

OUP accepted manuscript

Background

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are clinically severe respiratory disorders, and there are currently no Food and Drug Administration-approved drug therapies. It is of great interest to us that dimethyl fumarate (DMF) has been shown to have anti-inflammatory effects. The aim of this study was to investigate whether DMF could alleviate lipopolysaccharide(LPS)-induced ALI, and to explore its mechanism of action.

Materials and methods

We established a mice model of ALI with intratracheal instillation of LPS and intraperitoneal injection of DMF to treat ALI. The pathological damage and inflammatory response of lung tissues were observed by hematoxylin and eosin (H&E) staining, ELISA assay and western blot. ATP plus LPS was used for the establishment of ALI in vitro model, the therapeutic effects of DMF was explored by ELISA assay, RT-qPCR, western blot, and flow cytometry, and the therapeutic mechanisms of DMF was explored by administration of Brusatol (BT), a nuclear factor erythroid-2-related factor 2 (Nrf2) inhibitor.

Results

We found that intraperitoneal injection of DMF significantly reduced LPS-induced the pulmonary injury, pulmonary edema, and infiltration of inflammatory mediators. In LPS-induced ALI, NLRP3 inflammasome-mediated pyroptosis was markedly activated, followed by cleavage of caspase-1 and GSDMD. DMF inhibited the activation of the NLRP3 inflammasome and pyroptosis in both lung of ALI mice and ATP plus LPS-induced BEAS-2B cells. Mechanistically, DMF enhanced expressions of Nrf2, leading to inactivation of NLRP3 inflammasome and reduced pyroptosis in vivo and in vitro. Conversely, BT reduced the inhibitory effects of DMF on NLRP3 inflammasome and pyroptosis, and consequently blocked the improvement roles of DMF on ALI.

Conclusions

DMF could improve LPS-induced ALI via inhibiting NLRP3 inflammasome and pyroptosis, and that these effects were mediated by triggering Nrf2 expression, suggesting a therapeutic potential of DMF as an anti-inflammatory agent for ALI/ARDS treatment.

Hematological and biochemical investigations on the effect of curcumin and Thymoquinone in male mice exposed to Thioacetamide

Currently, living organisms are increasingly exposed to many toxic chemicals in the environment. These substances pose a threat to human life, other living organisms and ecosystem. In fact, there is an increasing requirement to search for safe therapeutic sources today. Medicinal plants and natural products have become of great importance globally because of their therapeutic potential and medicinal properties, as well as their availability and the absence of harmful side effects for most of them. The present study was designed to explore the potential protective effect of curcumin (CUR) and thymoquinone (TQ) in male rats exposed to thioacetamide (TAA). The experimental mice were divided into eight groups. Group 1 was served as control. Group 2 was exposed to 50 mg/ kg body weight of TAA. Group 3 was exposed to CUR and TAA. Mice of group 4 were treated with TQ and TAA. Mice of group 5 were exposed to CUR plus TQ and TAA. Group 6 was supplemented with CUR. Group 7 was subjected to TQ. Mice of group 8 were treated with CUR and TQ. Hematological and biochemical alterations were evaluated after one month. Significant increases of white blood corpuscles (WBC), alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), total bilirubin (TB), tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) values were observed in group 2, while the values of red blood corpuscles (RBC), hemoglobin (Hb(, hematocrit (Hct), glutathione (GSH) and superoxide dismutase (SOD) were statistically decreased. Treatment with CUR, TQ and their combination inhibited the hematological and biochemical alterations induced by TAA toxicity. Moreover, the most protective effect was observed in mice treated with CUR plus TQ. These new results suggested that the protective effect of CUR and TQ attributed to their antioxidant properties.

Hepatoprotective effects of methanolic extract of green tea against Thioacetamide-Induced liver injury in Sprague Dawley rats

ETHNOPHARMACOLOGICAL RELEVANCE

Since ancient times, herbal medicines have been applied in the treatment of cancer. Tea, derivative from the dried leaves of Camellia sinensis (L.) Kuntze plant is the most popular beverage globally after water and is available in various forms. Green tea has been expansively investigated for its beneficial properties of cancer prevention and therapy. The goal of the research: The current study was conducted to evaluate the hepaprotective character of methanolic green tea extract and its mechanism of action contrary to thioacetamide (TAA)-produced liver fibrosis of Sprague Dawley rats.

MATERIALS AND METHODS

Thirty rodents were equally placed in 5 clusters including normal control, TAA group as a positive control, silymarin as standard drug control, and treatment groups consisting of high dose and a low dose Camellia sinensis. Rats in experimental clusters by mouth fed with C. sinensis at 250 mg/kg or 500 mg/kg daily for 2 months. After 60 days, all rats were sacrificed. Blood specimens were gathered for liver biochemical examination. Livers of all groups were dissected out and subjected to histopathological examination through the Hematoxylin and Eosin stain, Masson trichrome, and immunohistochemistry stains (PCNA). Liver tissue homogenate was also analyzed for antioxidant activity parameters.

RESULTS

Gross morphological examination showed a regular liver architecture in C. sinensis fed collections compared to the TAA sets. Histology of rat's liver fed with C. sinensis showed an important decrease in the liver index with hepatic cells propagation, mild cellular injury, and immunostaining showed significant down-expression of proliferating cell nuclear antigen (PCNA). TAA produced liver fibrosis through a significant increase in serum alanine transferase, aspartate aminotransferase, alkaline phosphatase, and bilirubin. Total protein and albumin also decreased in the TAA group. Moreover, the reduction of antioxidant enzyme activity including superoxide dismutase and catalase as well as the increase in malondialdehyde was detected in the TAA control group. Meanwhile, an abnormal level of liver biochemical parameters was restored closer to the normal levels in serum of the C. sinensis-fed clusters. In addition, C. sinensis fed assemblies showed elevated antioxidative enzymes activity with a reduction in malondialdehyde level comparable to the levels in silymarin-treated rats.

CONCLUSIONS

Green tea potentially inhibited the progression of liver cirrhosis, down -regulation of PCNA proliferation, prevented oxidation of hepatocytes, recovered SOD and CAT enzymes, condensed MDA and reduced cellular inflammation.

Association of Type 1 diabetes with ulcerative colitis in BALB/c mice: Investigations on sex-specific differences

Diabetes comorbidity in ulcerative colitis (UC) has relevant clinical and therapeutic implications. The link between hyperglycemia and intestinal barrier function with respect to infection and inflammation consequences exists in diabetes. The present study was designed to decipher the molecular mechanisms associated with Type 1 Diabetes mellitus and the UC in both male and female BALB/c mice. Dextran sulfate sodium (DSS; 2.5%w/v) dissolved in drinking water was given for three cycles (each cycle; 7 days) with 7 days recovery period in-between to both male and female BALB/c mice. At the first recovery period, Streptozotocin (40 mg/kg; i.p.) was administered for 5 consecutive days in the case of male BALB/c mice; whereas the same procedure was repeated at the beginning of each recovery period in female animals. In the DSS + DB group of male animals, disease activity index, myeloperoxidase activity, nitrite level, plasma lipopolysaccharides, interleukin-1β, histological score, % fibrotic area, % TUNEL positive cells were significantly increased. Furthermore, protein expression of phosphorylated nuclear factor kappa light chain enhancer of activated B cells (pNFκB65), proliferating cell nuclear antigen, interleukin-6, apoptosis-associated speck-like protein containing a caspase-recruitment domain, and cysteine-containing aspartate-specific proteases-1 (caspase-1) significantly increased in the DSS + DB group of male animals as compared to female. The present study findings proved that hyperglycemic conditions exacerbated the pathological conditions in UC of male animals; whereas milder conditions developed in females.

Non-Alcoholic Fatty Liver Disease (NAFLD) in Patients with Psoriasis: A Review of the Hepatic Effects of Systemic Therapies

There is increasing interest in the association between psoriasis and non-alcoholic fatty liver disease (NAFLD), which is a prevalent liver disease characterized by excessive fat storage and inflammation that can progress to fibrosis and cancer. Patients with psoriasis have a two-fold higher risk to develop NAFLD and a higher risk to progress to more severe liver disease. Psoriasis and NAFLD share common risk factors such as smoking, alcohol consumption, and the presence of metabolic syndrome and its component disorders. In addition, both psoriasis and NAFLD hinge upon a systemic low-grade inflammation that can lead to a vicious cycle of progressive liver damage in NAFLD as well as worsening of the underlying psoriasis. Other important shared pathophysiological pathways include peripheral insulin resistance and oxidative stress. NAFLD should receive clinical awareness as important comorbidity in psoriasis. In this review, we assess the recent literature on the epidemiological and pathophysiological relationship of psoriasis and NAFLD, discuss the clinical implications of NAFLD in psoriasis patients, and summarize the hepatotoxic and hepatoprotective potential of systemic psoriasis therapies.

Dimethyl fumarate prevents acute lung injury related cognitive impairment potentially via reducing inflammation

OBJECTIVE

Dimethyl fumarate (DMF) has been reported to exert a protective role against diverse lung diseases and cognitive impairment-related diseases. Thus this study aimed to investigate its role on acute lung injury (ALI) and related cognitive impairment in animal model.

METHODS

C57BL/6 mice were divided into four groups: control group, DMF group, ALI group, and ALI + DMF group. For ALI group, the ALI mice model was created by airway injection of LPS (50 μL, 1 μg/μL); for ALI + DMF group, DMF (dissolved in 0.08% methylcellulose) was treated twice a day for 2 days, and on the third day, mice were injected with LPS for ALI modeling. Mice pre-administered with methylcellulose or DMF without LPS injection (PBS instead) were used as the control group and DMF group, respectively. Morris water maze test was performed before any treatment (0 h) and 6 h after LPS-induction (54 h) to evaluate the cognitive impairment of mice. Next, the brain edema and blood brain barrier (BBB) permeability of ALI mice were assessed by brain water content, Evans blue extravasation and FITC-Dextran uptake assays. In addition, the effect of DMF on the numbers of total cells and neutrophils, protein content in BALF were quantified; the inflammatory factors in BALF, serum, and brain tissues were examined by ELISA, qRT-PCR, and Western blot assays. The effect of DMF on the cognitive impairment-related factor HIF-1α level in lung and brain tissues was also examined by Western blot.

RESULTS

DMF reduced the numbers of total cells, neutrophils and protein content in BALF of ALI mice, inhibited the levels of IL-6, TNF-α and IL-1β in BALF, serum and brain tissues of ALI mice. The protein expressions of p-NF-κB/NF-κB and p-IKBα/IKBα was also suppressed by DMF in ALI mice. Morris water maze test showed that DMF alleviated the cognitive impairment in ALI mice by reducing the escape latency and path length. Moreover, DMF lessened the BBB permeability by decreasing cerebral water content, Evans blue extravasation and FITC-Dextran uptake in ALI mice. The HIF-1α levels in lung and brain tissues of ALI mice were also lessened by DMF.

CONCLUSION

In conclusion, DME had the ability to alleviate the lung injury and cerebral cognitive impairment in ALI model mice. This protective effect partly associated with the suppression of inflammation by DMF.

The Ameliorative Effects of Saikosaponin in Thioacetamide-Induced Liver Injury and Non-Alcoholic Fatty Liver Disease in Mice

Liver disorders are a major health concern. Saikosaponin-d (SSd) is an effective active ingredient extracted from Bupleurum falcatum, a traditional Chinese medicinal plant, with anti-inflammatory and antioxidant properties. However, its hepatoprotective properties and underlying mechanisms are unknown. We investigated the effects and underlying mechanisms of SSd treatment for thioacetamide (TAA)-induced liver injury and high-fat-diet (HFD)-induced non-alcoholic fatty liver disease (NAFLD) in male C57BL/6 mice. The SSd group showed significantly higher food intake, body weight, and hepatic antioxidative enzymes (catalase (CAT), glutathione peroxidase (GPx), and superoxide dismutase (SOD)) and lower hepatic cyclooxygenase-2 (COX-2), serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), interleukin (IL)-1β, tumor necrosis factor (TNF)-α, and fibroblast growth factor-21 (FGF21) compared with controls, as well as reduced expression of inflammation-related genes (nuclear factor kappa B (NF-κB) and inducible nitric oxide synthase (iNOS)) messenger RNA (mRNA). In NAFLD mice, SSd reduced serum ALT, AST, triglycerides, fatty acid–binding protein 4 (FABP4) and sterol regulatory element–binding protein 1 (SREBP1) mRNA, and endoplasmic reticulum (ER)-stress-related proteins (phosphorylated eukaryotic initiation factor 2α subunit (p-eIF2α), activating transcription factor 4 (ATF4), and C/EBP homologous protein (CHOP). SSd has a hepatoprotective effect in liver injury by suppressing inflammatory responses and acting as an antioxidant.

Simultaneous Modulation of NLRP3 Inflammasome and Nrf2/ARE Pathway Rescues Thioacetamide-Induced Hepatic Damage in Mice: Role of Oxidative Stress and Inflammation

Chronic tissue injury resulting in fibrosis of multiple organs, responsible for one-third of the death globally. Liver fibrosis is a common pathway/condition involved in all chronic liver diseases. Thioacetamide (TAA), a hepatotoxicant, was used to induce hepatic fibrosis. Anti-diabetic drug glibenclamide (GLB) possesses anti-inflammatory properties and inhibits NACHT, LRR, and PYD domains-containing protein 3 (NLRP3) inflammasome activation. Dimethyl fumarate (DMF), a multiple sclerosis drug, activates the nuclear factor erythroid 2-related factor 2 (Nrf2)/antioxidant response element (ARE) pathway and maintains the antioxidant status in the cell. The present study was designed to investigate (i) role of NLRP3 inflammasome and Nrf2/ARE pathway in TAA-induced hepatotoxicity and liver fibrosis, (ii) mechanism involved in GLB and DMF mediated hepatoprotection against TAA-induced hepatotoxicity, and (iii) additional/synergistic hepatoprotective effect of combination treatment with NLRP3 inhibition + Nrf2 activation or GLB + DMF or MCC950 + 4OI to reverse/ameliorate the experimental liver fibrosis completely. TAA was administered intraperitoneally to mice for seven consecutive weeks, and treatments of GLB, DMF, GLB + DMF, MCC950, 4OI, and MCC950 + 4OI were provided for the last three consecutive weeks. The intervention with GLB, DMF, GLB + DMF, MCC950, 4OI, and MCC950 + 4OI significantly protected TAA-induced oxidative stress and inflammatory conditions by improving biochemical, histological, and immunoexpression changes in mice. The GLB, DMF, and GLB + DMF intervention exhibited a better protective effect compared with MCC950, 4OI, and MCC950 + 4OI, which revealed that this specific inhibitor/activator possesses only NLRP3 inflammasome inhibitory/Nrf2 activatory properties. In contrast, the clinical drug GLB and DMF have several other beneficial effects, which are independent of NLRP3 inhibition and Nrf2 activation.

Nrf2 expression in pancreatic stellate cells promotes progression of cancer

It was previously identified that systemic Nrf2 deletion attenuates pancreatic cancer progression in a mutant K-ras/p53-expressing mouse model (KPC mouse). In this study, the type of cell that is responsible for the retarded cancer progression was elucidated. Human pancreatic cancers were first examined, and elevated expression of NRF2-target gene products in α-smooth muscle actin-positive cells was found, suggesting that pancreatic stellate cells (PSCs) are involved in this process. Closer examination of primary cultured PSCs from Nrf2-deleted mice revealed that the cells were less proliferative and retained a lower migration capacity. The conditioned medium of Nrf2-deleted PSCs exhibited reduced growth-stimulating effects in pancreatic cancer cells. KPC mouse-derived pancreatic cancer cells coinjected with wild-type PSCs developed significantly larger subcutaneous tumors in immunodeficient mice than those coinjected with Nrf2-deleted PSCs. These results demonstrate that Nrf2 actively contributes to the function of PSCs to sustain KPC cancer progression, thus, suggesting that Nrf2 inhibition in PSCs may be therapeutically important in pancreatic cancer.NEW & NOTEWORTHY This study identified that Nrf2 contributes to PSC activation. Nrf2 deletion in PSCs resulted in attenuation of cancer-promoting role. Nrf2 in PSCs could be an attractive therapeutic target in pancreatic cancer.

Dimethyl fumarate prevents cytotoxicity and apoptosis mediated by oxidative stress in human adipose-derived mesenchymal stem cells

BACKGROUND

The poor survival rate and undesirable homing of transplanted stem cells are the major challenges in stem cell therapy. Addressing the challenge would improve the therapeutic efficacy of these cells. Dimethyl fumarate (DMF) is an anti-inflammatory drug that exerts its effects through the activation of the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway. Therefore, its cytoprotective effects on human adipose-derived MSCs (hASCs) against various oxidative stresses have been investigated in this study.

METHODS AND RESULTS

hASCs were cultured with different concentrations of DMF to evaluate the cytotoxicity of DMF on hASCs using Cell Counting Kit-8 (CCK-8). Besides, the migration ability of the cells after DMF treatment was evaluated using the Transwell method. Furthermore, the expression of HO-1 and NQO-1 was determined using RT-PCR. The cytoprotective effects of DMF on hASCs against the oxidative stress caused by H₂O₂ and Ultra Violet (UV) were evaluated by assessing cell proliferation and apoptosis. Our results demonstrated that under oxidative stress conditions induced by H₂O₂ and UV, DMF increased the survival rate and proliferation of the cells and prevented apoptosis. Moreover, the expression of HO-1 and NQO-1 was upregulated in hASCs pretreated with DMF which confirms the activation of the Nrf2 pathway. However, DMF significantly decreased migration in hADSCs (P < 0.0001).

CONCLUSION

Our findings indicate that DMF enhances the proliferation capability and viability of hASCs and prevents their apoptosis in harsh stressful microenvironments. However, the applicability of DMF as a cytoprotective factor for the augmentation of hASCs requires in-depth preclinical and clinical studies.

Modulation of the fecal microbiome and metabolome by resistant dextrin ameliorates hepatic steatosis and mitochondrial abnormalities in mice

Targeting the gut-liver axis by manipulating the intestinal microbiome is a promising therapy for nonalcoholic fatty liver disease (NAFLD). This study modulated the intestinal microbiota to explore whether resistant dextrin, as a potential prebiotic, could ameliorate high-fat diet (HFD)-induced hepatic steatosis in C57BL/6J mice. After two months of feeding, significant hepatic steatosis with mitochondrial dysfunction was observed in the HFD-fed mice. However, the concentrations of triglycerides and malondialdehyde in liver tissue and the levels of alanine aminotransferase and aspartate aminotransferase in the serum of mice fed an HFD plus resistant dextrin diet (HFID) were significantly decreased compared to the HFD-fed mice. Additionally, hepatic mitochondrial integrity and reactive oxygen species accumulation were improved in HFID-fed mice, ameliorating hepatic steatosis. The fecal microbiome of HFD-fed mice was enriched in Bifidobacterium, Lactobacillus, and Globicatella, while resistant dextrin increased the abundance of Parabacteroides, Blautia, and Dubosiella. Major changes in fecal metabolites were confirmed for HFID-fed mice, including those related to entero-hepatic circulation (i.e., bile acids), tryptophan metabolism (e.g., indole derivatives), and lipid metabolism (e.g., lipoic acid), as well as increased antioxidants including isorhapontigenin. Furthermore, resistant dextrin decreased inflammatory cytokine levels and intestinal permeability and ameliorated intestinal damage. Together, these findings augmented current knowledge on prebiotic treatment for NAFLD.

Activation of the Nrf2/HO-1 signaling pathway by dimethyl fumarate ameliorates complete Freund's adjuvant-induced arthritis in rats

The nuclear factor erythroid 2-related factor (Nrf2) signaling pathway has recently emerged as a novel therapeutic target in treating various diseases. Therefore, the present study aimed to assess the protective role of the Nrf2 activator, dimethyl fumarate (DMF) in the complete Freund's adjuvant (CFA)- induced arthritis model. DMF (25, 50, and 100 mg/kg) and dexamethasone (2 mg/kg) were orally administered for 14 days. Pain-related tests, paw volume, and arthritic scores were measured weekly. Serum TNF-α, IL-1β, cyclic citrullinated peptide (CCP), C-reactive protein (CRP), and rheumatoid factor (RF) levels were estimated. Nitrite, malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione (GSH), catalase (CAT), and myeloperoxidase (MPO) levels were also evaluated. NF-κB, Nrf2, HO-1, and COX-2 levels were estimated in the joint tissue. DMF treatment exerted anti-arthritic activity by enhancing the nociceptive threshold, improving arthritis scores, and reducing paw edema. Also, DMF suppressed changes in oxidative stress markers and inflammatory mediators and enhanced Nrf2 and HO-1 levels in CFA-injected rats. These findings indicate that the anti-arthritic activity of DMF may be mediated by the activation of the Nrf2/HO-1 pathway, which reduced oxidative damage and inflammation.

The intervention of tert-butylhydroquinone protects ethanol-induced gastric ulcer in type II diabetic rats: the role of Nrf2 pathway

Ethanol consumption increases the prevalence of gastric ulcer (GU) in rats with type II diabetes (T2D). Induction of GU by absolute ethanol (5 mL/kg or 3.94 g/kg) in the animal model resembles human ulcer characteristics. The aim was to investigate the role of the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway in the treatment of GU in diabetic condition. The rats were exposed to absolute ethanol 1 h before sacrifice and T2D was induced by combined exposure of high-fat diet and low dose streptozotocin. Pretreatment of tert-butylhydroquinone (tBHQ) (25 and 50 mg/kg), metformin (500 mg/kg), and omeprazole (20 mg/kg) were given once daily for last three consecutive weeks. In ethanol-exposed diabetic rats, pretreatment with tBHQ, omeprazole, and metformin reduced gastric mucosal lesion, ulcer index, histological alterations, malondialdehyde level, and apoptosis. Furthermore, the intervention of tBHQ, omeprazole, and metformin improved the integrity of the stomach mucosa, glutathione, gastric pH, collagen, and goblet cells. tBHQ treatment improved ethanol-induced alterations of Nrf2, catalase, heat shock protein 70 (HSP70), NF-κB, and endothelin-1 expressions in diabetic rats. In diabetic conditions, the incidence of GU is increased due to elevated levels of reactive oxygen species, inflammatory mediators, depleted levels of cellular antioxidants, and altered gastric parameters. The tBHQ intervention could be a rational strategy to protect these changes.

Chlorogenic acid, quercetin, coenzyme Q10 and silymarin modulate Keap1-Nrf2/heme oxygenase-1 signaling in thioacetamide-induced acute liver toxicity

BACKGROUND AND AIMS

The normal functioning of Kelch-like ECH-associated protein-1 (Keap1)/nuclear factor erythroid 2-related factor 2 (Nrf2) complex is necessary for the cellular protection against oxidative stress. We investigated the effect of chlorogenic acid (CGA), quercetin (Qt), coenzyme Q10 (Q10) and silymarin on the expression of Keap1/Nrf2 complex and its downstream target; heme oxygenase-1 (HO-1) as well as inflammation and apoptosis in an acute liver toxicity model induced by thioacetamide (TAA).

MAIN METHODS

Wistar rats were divided into 13 groups: Control, silymarin, CGA, Qt, Q10, TAA (single dose 50 mg/kg, i.p.), TAA + silymarin (400 mg/kg, p.o.), TAA + CGA (100 & 200 mg/kg, p.o.), TAA + Qt (200 &300 mg/kg, p.o.) and TAA+ Q10 (30&50 mg/kg, p.o.) and treated for 8 days.

KEY FINDINGS

The results showed improved liver functions and hepatic tissue integrity in all tested doses of TAA + silymarin, TAA + CGA, TAA + Qt and TAA + Q10 groups compared to the TAA group. Furthermore, these groups showed significantly lower ROS, malondialdehyde and nitric oxide levels but higher glutathione content and superoxide dismutase activity compared to the TAA group, p < 0.05. In these groups, Keap1 expression was significantly decreased while Nrf2 expression and HO-1 activity were increased. In addition, the number of apoptotic cells and the expression level of TNF-α in the liver tissues were significantly decreased compared to the TAA group.

SIGNIFICANCE

CGA, Qt, Q10 and silymarin protect against TAA-induced acute liver toxicity via antioxidant, anti-inflammatory, anti-apoptotic activities and regulating Keap1-Nrf2/HO-1 expression.

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.

Dimethyl fumarate protects against intestinal ischemia/reperfusion lesion: Participation of Nrf2/HO-1, GSK-3β and Wnt/β-catenin pathway

OBJECTIVE

Dimethyl fumarate (DMFU), a known Nrf2 activator, has proven its positive effect in different organs against ischemia/reperfusion (Is/Re) injury. Nevertheless, its possible impact to modulate intestinal Is/Re-induced injury has not been previously demonstrated before. Hence, this study aimed to investigate DMFU mechanistic maneuver against intestinal Is/Re.

METHODS

To accomplish this goal, Wistar rats were allocated into four groups; Sham-operated (SOP), intestinal Is/Re (1 h/6 h), and 14 days pre-treated DMFU (15 and 25 mg/kg/day, p.o).

RESULTS

The mechanistic maneuver divulged that DMFU safeguarded the intestine partly via amplifying the expression/content of Nrf2 along with enhancing its downstream, HO-1 expression/content. In addition, DMFU lessened GSK-3β expression/content accompanied by enriching β-catenin expression/content. The antioxidant action was affirmed by enhancing total antioxidant capacity, besides reducing MDA, iNOS, and its by-product, NOx. The DMFU action entailed anti-inflammatory character manifested by down-regulation of expression/content NF-κB with subsequent rebating the contents of TNF-α, IL-1β, and P-selectin, as well as MPO activity. Moreover, DMFU had anti-apoptotic nature demonstrated through enriching Bcl-2 level and diminishing that of caspase-3.

CONCLUSION

DMFU purveyed tenable novel protective mechanisms and mitigated events associated with intestinal Is/Re mischief either in the lower or the high dose partly by amending of oxidative stress and inflammation through the modulation of Nrf2/HO-1, GSK-3β, and Wnt/β-catenin pathways.

NRF2 and PPAR-γ Pathways in Oligodendrocyte Progenitors: Focus on ROS Protection, Mitochondrial Biogenesis and Promotion of Cell Differentiation

An adequate protection from oxidative and inflammatory reactions, together with the promotion of oligodendrocyte progenitor (OP) differentiation, is needed to recover from myelin damage in demyelinating diseases. Mitochondria are targets of inflammatory and oxidative insults and are essential in oligodendrocyte differentiation. It is known that nuclear factor-erythroid 2-related factor/antioxidant responsive element (NRF2/ARE) and peroxisome proliferator-activated receptor gamma/PPAR-γ response element (PPAR-γ/PPRE) pathways control inflammation and overcome mitochondrial impairment. In this study, we analyzed the effects of activators of these pathways on mitochondrial features, protection from inflammatory/mitochondrial insults and cell differentiation in OP cultures, to depict the specificities and similarities of their actions. We used dimethyl-fumarate (DMF) and pioglitazone (pio) as agents activating NRF2 and PPAR-γ, respectively, and two synthetic hybrids acting differently on the NRF2/ARE pathway. Only DMF and compound 1 caused early effects on the mitochondria. Both DMF and pio induced mitochondrial biogenesis but different antioxidant repertoires. Moreover, pio induced OP differentiation more efficiently than DMF. Finally, DMF, pio and compound 1 protected from tumor necrosis factor-alpha (TNF-α) insult, with pio showing faster kinetics of action and compound 1 a higher activity than DMF. In conclusion, NRF2 and PPAR-γ by inducing partially overlapping pathways accomplish complementary functions aimed at the preservation of mitochondrial function, the defense against oxidative stress and the promotion of OP differentiation.