Celastrol induces ferroptosis in activated HSCs to ameliorate hepatic fibrosis via targeting peroxiredoxins and HO-1

Ferroptosis is a form of regulated cell death, characterized by excessive membrane lipid peroxidation in an iron- and ROS-dependent manner. Celastrol, a natural bioactive triterpenoid extracted from Tripterygium wilfordii, shows effective anti-fibrotic and anti-inflammatory activities in multiple hepatic diseases. However, the exact molecular mechanisms of action and the direct protein targets of celastrol in the treatment of liver fibrosis remain largely elusive. Here, we discover that celastrol exerts anti-fibrotic effects via promoting the production of reactive oxygen species (ROS) and inducing ferroptosis in activated hepatic stellate cells (HSCs). By using activity-based protein profiling (ABPP) in combination with bio-orthogonal click chemistry reaction and cellular thermal shift assay (CETSA), we show that celastrol directly binds to peroxiredoxins (PRDXs), including PRDX1, PRDX2, PRDX4 and PRDX6, through the active cysteine sites, and inhibits their anti-oxidant activities. Celastrol also targets to heme oxygenase 1 (HO-1) and upregulates its expression in activated-HSCs. Knockdown of PRDX1, PRDX2, PRDX4, PRDX6 or HO-1 in HSCs, to varying extent, elevated cellular ROS levels and induced ferroptosis. Taken together, our findings reveal the direct protein targets and molecular mechanisms via which celastrol ameliorates hepatic fibrosis, thus supporting the further development of celastrol as a promising therapeutic agent for liver fibrosis.

Recommendations for the use of the acetaminophen hepatotoxicity model for mechanistic studies and how to avoid common pitfalls

Acetaminophen (APAP) is a widely used analgesic and antipyretic drug, which is safe at therapeutic doses but can cause severe liver injury and even liver failure after overdoses. The mouse model of APAP hepatotoxicity recapitulates closely the human pathophysiology. As a result, this clinically relevant model is frequently used to study mechanisms of drug-induced liver injury and even more so to test potential therapeutic interventions. However, the complexity of the model requires a thorough understanding of the pathophysiology to obtain valid results and mechanistic information that is translatable to the clinic. However, many studies using this model are flawed, which jeopardizes the scientific and clinical relevance. The purpose of this review is to provide a framework of the model where mechanistically sound and clinically relevant data can be obtained. The discussion provides insight into the injury mechanisms and how to study it including the critical roles of drug metabolism, mitochondrial dysfunction, necrotic cell death, autophagy and the sterile inflammatory response. In addition, the most frequently made mistakes when using this model are discussed. Thus, considering these recommendations when studying APAP hepatotoxicity will facilitate the discovery of more clinically relevant interventions.

Cinnamon oil against acetaminophen-induced acute liver toxicity by attenuating inflammation, oxidative stress and apoptosis

Acetaminophen (APAP) is used as a primary drug due to its antipyretic and analgesic activity. The mechanism of action of APAP toxicity in the liver is due to the depletion of glutathione which elicited free radicals generation. Therefore, the objective of our work is to investigate the APAP induced liver damage and its repair by free radical scavenging activity of cinnamon oil (CO) in male Wistar rats. To investigate the effects of CO at different doses (50, 100 and 200 mg/kg b.w.), animals were given a single oral dose of CO per day for 14 days between 12:00−1:00 PM. The biochemical changes, imbalance in oxidative markers, interleukins, caspases and histopathological studies were determined for quantifying the hepatoprotective effect of CO. One dose of APAP (2 g/kg b.w.) results in significant hepatotoxicity and marked increase the serum markers alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), bilirubin, albumin, total protein, content of lipid peroxidation (LPO), interleukins (IL-1β, IL-6), caspase-3, -9 expression, DNA fragmentation and histopathological changes were observed. Significant decrease in the levels of LPO, interleukins IL-1β, IL-6, caspase-3, -9 expressions, qualitative as well as quantitative determination of DNA fragments and histopathological changes were reversed by the administration of CO dose dependently. Furthermore, it also restores the depleted activity of antioxidative enzymes. Our study shows that an imbalance in the oxidative parameter in the liver by APAP is restored by treating the animals with CO.

Vanadium: Risks and possible benefits in the light of a comprehensive overview of its pharmacotoxicological mechanisms and multi-applications with a summary of further research trends

BACKGROUND

Vanadium (V) is an element with a wide range of effects on the mammalian organism. The ability of this metal to form organometallic compounds has contributed to the increase in the number of studies on the multidirectional biological activity of its various organic complexes in view of their application in medicine.

OBJECTIVE

This review aims at summarizing the current state of knowledge of the pharmacological potential of V and the mechanisms underlying its anti-viral, anti-bacterial, anti-parasitic, anti-fungal, anti-cancer, anti-diabetic, anti-hypercholesterolemic, cardioprotective, and neuroprotective activity as well as the mechanisms of appetite regulation related to the possibility of using this element in the treatment of obesity. The toxicological potential of V and the mechanisms of its toxic action, which have not been sufficiently recognized yet, as well as key information about the essentiality of this metal, its physiological role, and metabolism with certain aspects on the timeline is collected as well. The report also aims to review the use of V in the implantology and industrial sectors emphasizing the human health hazard as well as collect data on the directions of further research on V and its interactions with Mg along with their character.

RESULTS AND CONCLUSIONS

Multidirectional studies on V have shown that further analyses are still required for this element to be used as a metallodrug in the fight against certain life-threatening diseases. Studies on interactions of V with Mg, which showed that both elements are able to modulate the response in an interactive manner are needed as well, as the results of such investigations may help not only in recognizing new markers of V toxicity and clarify the underlying interactive mechanism between them, thus improving the medical application of the metals against modern-age diseases, but also they may help in development of principles of effective protection of humans against environmental/occupational V exposure.

Gastroprotective and anti-inflammatory effects of Prunus cerasus phytochemicals and their possible mechanisms of action

Prunus cerasus (P. cerasus) is an alternative-medicine used traditionally for amelioration of chronic-ailments marked by elevation in oxidative-stress like neuropathy. The oxidative-stress control was reported to ameliorate the inflammatory-process. This study aimed to phytochemically-investigate P. cerasus most-active phytochemicals utilizing in-vivo biological models to explore their gastroprotective, anti-inflammatory, and antinociceptive potentials and their possible mechanisms of action. Sonication with EtAc was used to extract P. cerasus fruit (Scf), and seed (Scs). The phytochemical-investigation of Scf was performed by RP-HPLC, while that of Scs was explored utilizing GC-FID. A bio-guided-fraction and isolation method was done utilizing column-chromatography, and have shown that cyanidin-3-glucoside (Cy3G) was the most-active constituent in Scf, while linoleic-acid (LA) was the most-active constituent in Scs. Scf, Scs, Cy3G, and LA significantly (p ˂ 0.05) protected the gastric-mucosa against HCl/EtOH-induced gastric-lesions. Scs (200 mg/kg) has shown the most gastroprotective-potentials, and had comparable-results to ranitidine (50 mg/kg). Scf, Scs, Cy3G, and LA have shown significant anti-inflammatory and antinociceptive potentials against carrageenan induced-edema and nociceptive-pain, respectively, where Scs (200 mg/kg) has shown the most anti-inflammatory and antinociceptive potentials, and had comparable results to ibuprofen (100 mg/kg). Scf, Scs, Cy3G, and LA have counter-acted carrageenan-induced oxidative-stress markers, with increased serum-catalase and reduced-glutathione levels, and decreased lipid-peroxidation. Histopathological-studies demonstrated gastroprotective potentials, regeneration and improvement of the spleen-structural architecture when treated with highest doses of Scs and Scf. The reduction of the pro-inflammatory TNF-alpha and IL-6, and elevation the anti-inflammatory factor IL-10 levels, spleen regenerative-capacity and oxidative-stress amelioration might be the main-mechanism responsible for P. cerasus anti-inflammatory potentials. P. cerasus appears to aid in ameliorating the inflammatory process, and reducing pain-thresholds while preserving the stomach.

Nephrotoxicity and highly active antiretroviral therapy: Mitigating action of Momordica charantia

Momordica charantia (M. charantia) is known for its antioxidant and antidiabetic properties. The aim of this study is to investigate the renoprotective effects of M. charantia in rats following treatment with highly active antiretroviral therapy (HAART) regimen triplavar. Adult male Sprague-Dawley rats weighing 178.1-220.5 g (n = 36) were divided into six groups (A-F) with each group comprising of six (n = 6) rats. The drugs and extract were administered via oral gavage. The therapeutic dose of triplavar was adjusted using the human therapeutic dose equivalent for the rat model. Animals were euthanized on the tenth week with kidneys removed for examination and blood obtained via cardiac puncture. Levels of oxidative stress enzymes (superoxide dismutase-SOD, catalase-CAT, and reduced glutathione-GSH) were significantly lowered in all groups not receiving M. charantia. The levels of thiobarbituric acid reactive substances (TBARS) were increased resulting in free radical formation via auto-oxidation. Renal parameters showed no albuminuria, normal blood urea nitrogen (BUN), serum creatinine (SCr) and electrolytes in groups treated with M. charantia. HAART treated (Group B) showed severe albuminuria, a significantly (p < 0.05) raised BUN and SCr and gross electrolyte disturbances. Blood glucose levels were significantly raised in groups not receiving the adjuvant M. charantia (p < 0.05). Histopathology in HAART treated animals showed glomerular capillary abnormalities and cellular infiltrations while M. charantia treated animals showed an essentially normal glomerular appearance with capillary loops and normal cytoarchitecture. In conclusion M. charantia extract administration improved blood glucose levels, restored renal histology, reinstate renal function, reduce body weight loss and restores hyperglycemia.

The para isomer of dinitrobenzene disrupts redox homeostasis in liver and kidney of male wistar rats

Background

Para-Dinitrobenzene (p-DNB) is one of the isomers of dinitrobenzene which have been detected as environmental toxicants. Skin irritation and organ toxicities are likely for industrial workers exposed to p-DNB. This study evaluated the effect of sub-chronic exposure of rats to p-DNB on cellular redox balance, hepatic and renal integrity.

Methods

Forty eight male Wistar rats weighing 160–180 g were administered 50, 75, 1000 and 2000 mg/kg b.wt (body weight) of p-DNB or an equivalent volume of vehicle (control) orally and topically for 14 days. After the period of treatment, the activities of kidney and liver catalase (CAT), alkaline phosphatase (ALP) and superoxide dismutase (SOD) as well as extent of renal and hepatic lipid peroxidation (LPO) were determined. Serum ALP activity and plasma urea concentration were also evaluated.

Results

Compared with control animals, p-DNB -administered rats showed decrease in the body and relative kidney and liver weights as well as increased renal and hepatic hydrogen peroxide and lipid peroxidation levels accompanied by decreased superoxide dismutase and catalase activities. However, p-DNB caused a significant increase in plasma urea concentration and serum, liver and kidney ALP activities relative to control. In addition, p-DNB caused periportal infiltration, severe macro vesicular steatosis and hepatic necrosis in the liver.

Conclusions

Our findings show that sub-chronic oral and sub-dermal administration of p-DNB may produce hepato-nephrotoxicity through oxidative stress.

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Activities of kidney and liver catalase and superoxide dismutase were decreased by p-DNB.

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p-DNB increased serum, liver and kidney activity of alkaline phosphatase.

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Plasma urea concentration was increased by p-DNB.

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Lipid peroxidation and H₂O₂ level were increased by p-DNB.

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p-DNB caused histopathological changes in liver and kidney tissues.

Blood brain barrier permeability of (-)-epigallocatechin gallate, its proliferation-enhancing activity of human neuroblastoma SH-SY5Y cells, and its preventive effect on age-related cognitive dysfunction in mice

BACKGROUND

The consumption of green tea catechins (GTCs) suppresses age-related cognitive dysfunction in mice. GTCs are composed of several catechins, of which epigallocatechin gallate (EGCG) is the most abundant, followed by epigallocatechin (EGC). Orally ingested EGCG is hydrolyzed by intestinal biota to EGC and gallic acid (GA). To understand the mechanism of action of GTCs on the brain, their permeability of the blood brain barrier (BBB) as well as their effects on cognitive function in mice and on nerve cell proliferation in vitro were examined.

METHODS

The BBB permeability of EGCG, EGC and GA was examined using a BBB model kit. SAMP10, a mouse model of brain senescence, was used to test cognitive function in vivo. Human neuroblastoma SH-SY5Y cells were used to test nerve cell proliferation and differentiation.

RESULTS

The in vitro BBB permeability (%, in 30 min) of EGCG, EGC and GA was 2.8±0.1, 3.4±0.3 and 6.5±0.6, respectively. The permeability of EGCG into the BBB indicates that EGCG reached the brain parenchyma even at a very low concentration. The learning ability of SAMP10 mice that ingested EGCG (20 mg/kg) was significantly higher than of mice that ingested EGC or GA. However, combined ingestion of EGC and GA showed a significant improvement comparable to EGCG. SH-SY5Y cell growth was significantly enhanced by 0.05 µM EGCG, but this effect was reduced at higher concentrations. The effect of EGC and GA was lower than that of EGCG at 0.05 µM. Co-administration of EGC and GA increased neurite length more than EGC or GA alone.

CONCLUSION

Cognitive dysfunction in mice is suppressed after ingesting GTCs when a low concentration of EGCG is incorporated into the brain parenchyma via the BBB. Nerve cell proliferation/differentiation was enhanced by a low concentration of EGCG. Furthermore, the additive effect of EGC and GA suggests that EGCG sustains a preventive effect after the hydrolysis to EGC and GA.

Acrolein Is a Pathogenic Mediator of Alcoholic Liver Disease and the Scavenger Hydralazine Is Protective in Mice

BACKGROUND & AIMS

Alcoholic liver disease (ALD) remains a major cause of morbidity and mortality, with no Food and Drug Administration-approved therapy. Chronic alcohol consumption causes a pro-oxidant environment and increases hepatic lipid peroxidation, with acrolein being the most reactive/toxic by-product. This study investigated the pathogenic role of acrolein in hepatic endoplasmic reticulum (ER) stress, steatosis, and injury in experimental ALD, and tested acrolein elimination/scavenging (using hydralazine) as a potential therapy in ALD.

METHODS

In vitro (rat hepatoma H4IIEC cells) and in vivo (chronic+binge alcohol feeding in C57Bl/6 mice) models were used to examine alcohol-induced acrolein accumulation and consequent hepatic ER stress, apoptosis, and injury. In addition, the potential protective effects of the acrolein scavenger, hydralazine, were examined both in vitro and in vivo.

RESULTS

Alcohol consumption/metabolism resulted in hepatic accumulation of acrolein-protein adducts, by up-regulation of cytochrome P4502E1 and alcohol dehydrogenase, and down-regulation of glutathione-s-transferase-P, which metabolizes/detoxifies acrolein. Alcohol-induced acrolein adduct accumulation led to hepatic ER stress, proapoptotic signaling, steatosis, apoptosis, and liver injury; however, ER-protective/adaptive responses were not induced. Notably, direct exposure to acrolein in vitro mimicked the in vivo effects of alcohol, indicating that acrolein mediates the adverse effects of alcohol. Importantly, hydralazine, a known acrolein scavenger, protected against alcohol-induced ER stress and liver injury, both in vitro and in mice.

CONCLUSIONS

Our study shows the following: (1) alcohol consumption triggers pathologic ER stress without ER adaptation/protection; (2) alcohol-induced acrolein is a potential therapeutic target and pathogenic mediator of hepatic ER stress, cell death, and injury; and (3) removal/clearance of acrolein by scavengers may have therapeutic potential in ALD.

Alzheimer's disease like pathology induced six weeks after aggregated amyloid-beta injection in rats: increased oxidative stress and impaired long-term memory with anxiety-like behavior

OBJECTIVES

Amyloid-beta (Aβ) peptide deposition into insoluble plaques is a pathological hallmark of Alzheimer's disease (AD), but soluble oligomeric Aβ is considered to be more potent and has been hypothesized to directly impair learning and memory. Also, evidences from some clinical studies indicated that Aβ oligomer formation is the major cause for early AD onset. However, the biochemical mechanism involved in the oligomer-induced toxicity is not very well addressed. So, thise present study was undertaken to study the effects of single intracerebroventricular (icv) injection of protofibrillar Aβ 1-42 on the behavioral and biochemical profile in rats.

METHODS

Rats were divided into two groups (n = 8 per group): (1) sham control group and (2) Aβ 1-42 injected group. A single dose of protofibrillar Aβ 1-42 (5 ul) through icv injection was bilaterally administered into the dorsal hippocampus, while sham control animals were administered with 5 µl of vehicle.

RESULTS

The results demonstrated that the protofibrillar Aβ significantly inhibited long-term memory retention and increased anxiety levels as shown by the behavioral studies. The amyloid deposits were present inside the brain even six weeks after injection as confirmed by thioflavin-T staining and the neurodegeneration induced by these deposits was confirmed by Nissl's staining in hippocampal and cortical regions. The amyloid aggregates induced reactive oxygen species (ROS) production, acetylcholinesterase activity, nitrite levels, lipid peroxidation, and inhibited antioxidant enzyme activity in hippocampus, cortex, and striatum regions of rat brain after six weeks.

DISCUSSION

The present study indicated that protofibrillar Aβ 1-42 injection altered long term memory, induced anxiety-like behavior and also developed Alzheimer's disease like pathology in rats.

Oral administration of Nigella sativa oil ameliorates the effect of cisplatin on membrane enzymes, carbohydrate metabolism and oxidative damage in rat liver

Cisplatin (CP) is a potent anti-cancer drug widely used against solid tumors. However, it exhibits pronounced adverse effects including hepatotoxicity. Several strategies were attempted to prevent CP hepatotoxicity but were not found suitable for therapeutic application. Nigella sativa has been shown to prevent/reduce the progression of certain type of cardiovascular, kidney and liver diseases. Present study investigates whether N. sativa oil (NSO) can prevent CP induced hepatotoxic effects. Rats were divided into four groups viz. control, CP, NSO and CPNSO. Animals in CPNSO and NSO group were administered NSO (2 ml/kg bwt, orally) with or without single hepatotoxic dose of CP (6 mg/kg bwt, i.p.) respectively. CP hepatotoxicity was recorded by increased serum ALT and AST activities. CP treatment caused oxidant/antioxidant imbalances as reflected by increased lipid peroxidation and decreased enzymatic and non-enzymatic antioxidants. Furthermore, the activities of various carbohydrate metabolism and membrane enzymes were altered by CP treatment. In contrast, NSO administration to CP treated rats, markedly ameliorated the CP elicited deleterious alterations in liver. Histopathological observations showed extensive liver damage in CP treated animals while greatly reduced tissue injury in CPNSO group. In conclusion, NSO appears to protect CP induced hepatotoxicity by improving energy metabolism and strengthening antioxidant defense mechanism.

Paraquat exposure induces behavioral deficits in larval zebrafish during the window of dopamine neurogenesis

Exposure to environmental risk factors such as herbicides in early life has been proposed to play important roles in the development of neurodegenerative disorders in adult life. To test this hypothesis, we used a zebrafish model to link the herbicide paraquat (PQ) to disease etiology. Strikingly, treatment of 18 hpf embryonic zebrafish with low-dose PQ treatment (0.04 ppm, lower than the accepted human daily exposure) resulted in 50% display of neurodegenerative phenotypes and motor deficits at various developmental stages (segmentation to larval stage). Wide arrays of biomarkers have been employed to delineate the toxic responses which include lipid peroxidation, glutathione (GSH) and apoptosis studies. A decrease in the GSH levels, increase in lipid peroxidation and apoptosis, respectively, were observed at various developmental stages. Unexpectedly, we show that the exposure to paraquat during the window of dopamine neurogenesis causes Parkinsonian like motor defects in later life by perturbing cholinergic system due to oxidative stress.

Gymnemasylvestre derived compounds inhibit GSH depletion and increase cGMP and nitric oxide to attenuate advanced glycation end products induced hypertrophic growth in renal tubular epithelial cells

The accumulation of advanced glycation end products (AGE) plays significant role in developing tubular hypertrophy during diabetic nephropathy (DN). Reactive oxygen species and nitric oxide (NO) are directly involved in the progression of DN. We have studied the effect of standardized Gymnemasylvestre organic extract (GE) on AGE induced cellular hypertrophy using rat renal tubular epithelial cells (NRK 52E). AGE (400 μg/ml) induced cytotoxicity to NRK 52E cells as determined by MTT assay at 0–72 h. We report cellular hypertrophy mediated cytotoxicity by AGE which was the result of significant reduction in the cellular nitric oxide and cGMP levels associated with increased lipid peroxidation and antioxidant depletion (P < 0.05). Upon treatment with GE the cell viability was increased with reduced cellular hypertrophy by 1.7 folds when compared to AGE treated group. GE could significantly increase NO by 1.9 folds and cGMP by 2.8 folds and inhibited GSH depletion by 50% during AGE induced toxicity. The antioxidant enzyme activity of catalase was increased by 50% while, glutathione peroxidase and superoxide dismutase enzyme activities were significantly increased by 42% and 67% with decreased lipid peroxidation (49%) upon GE treatment. Thus, GE attenuates AGE induced hypertrophic growth by inhibiting GSH depletion and partly through increased NO/cGMP signaling.

Ashwagandha (Withania somnifera) supercritical CO2 extract derived withanolides mitigates Bisphenol A induced mitochondrial toxicity in HepG2 cells

Bisphenol A (BPA) safety aspects on human health are debated extensively for long time. In the present study, we have studied the toxicity induced by BPA at no observed adverse effect level (NOAEL) using HepG2 cells. We report that BPA at 100 nM induced cytotoxicity to HepG2 cells as determined by MTT assay at 0-72 h. The toxicity was result of reduced oxygen consumption and reduced mitochondrial membrane potential associated with decreased ATP production. The BPA treatment resulted in increase of malondialdehyde (MDA) content with decreased glutathione and other antioxidant enzymes. BPA derived toxicity is a concern to human health and alternative non-toxic natural products/derivatives or adjuvants that serve as antidote will be relevant. In this context, Ashwagandha (Withania somnifera) a widely used herb to treat arthritis, rheumatism and to improve longevity for time immemorial is investigated for its antidote effect. Ashwagandha supercritical CO₂ extract derived Withanolides (ADW) at 100 μg/ml protect HepG2 cells from BPA induced toxicity by suppressing mitochondrial damage and increased ATP production. Further, cellular MDA content was significantly suppressed with increased non-enzymic and antioxidant enzyme activities. These findings derived from the present study suggest the beneficial effect of ADW in mitigating BPA induced mitochondrial toxicity in HepG2 cells.

Phyllanthin of Standardized Phyllanthus amarus Extract Attenuates Liver Oxidative Stress in Mice and Exerts Cytoprotective Activity on Human Hepatoma Cell Line

BACKGROUND

Phyllanthus amarus, a traditional herbal liver-protecting medicine, is known to contain an active ingredient phyllanthin. Many research studies and clinical trials performed in the past using this plant have given contentious results which clearly accentuates the need for the standardization of the extracts.

AIM

In this study, P. amarus extract was standardized for phyllanthin content by high performance thin layer chromatography (HPTLC) and high performance liquid chromatography (HPLC) analysis. The preventive role of a standardized extract of P. amarus against CC14-induced hepatotoxicity in vivo and in vitro using mice model and human hepatoma HepG2 cell line, respectively, was investigated.

METHODS

Phyllanthin was used as a marker phytochemical for the standardization of P. amarus extract. The extracts were verified for phyllanthin content by HPTLC and HPLC. Female mice were orally administered with CCl4 either with or without standardized P. amarus extract in three different doses. Similarly, the cytoprotective role of the standardized extract in vitro was studied in HepG2 cell line.

RESULTS

Oral administration of CCl4 resulted in increased oxidative stress, decreased antioxidative defense, and liver injury. Treatment with P. amarus along with CCl4 significantly mitigated the increase in activities of liver marker enzymes, lipid peroxidation, and bilirubin content. It also increased the antioxidant enzymatic and non-enzymatic defense parameter levels. The results of the in vitro study conducted in HepG2 cells indicated that the hepatotoxin lowered 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (Mil) metabolism and increased the release of transaminases which were corrected with co-incubation with P. amarus.

CONCLUSION

The study established a significant liver-protecting role of standardized P. amarus extract due to the presence of active ingredient phyllanthin.