Resveratrol inhibits cell growth by inducing cell cycle arrest in activated hepatic stellate cells

The Application of Resveratrol Derivatives in Oral Cells Reduces the Oxidative Stress Induced by Glucocorticoids

Oxidative stress and high levels of reactive oxygen species (ROS) are linked to various age-related diseases and chronic conditions, including damage to oral tissues. Dexamethasone (DEX), a widely used glucocorticoid in dentistry, can have side effects like increased ROS production and delayed wound healing. Resveratrol (RSV) is known for its antioxidant properties, but its limited bioavailability hinders its clinical use. This study investigated the potential of two RSV derivatives (1d and 1h) to address these limitations. The antioxidant abilities of 1d and 1h (5 μM) against DEX-induced oxidative stress (200 μM) were evaluated in human gingival fibroblasts (hGFs) and osteoblasts (hOBs). The effects of these compounds on cell viability, morphology, ROS levels, SOD activity, gene expression, and collagen production were evaluated. RSV derivatives, under DEX-induced oxidative stress condition, improved cell growth at 72 h (191.70 ± 10.92% for 1d+DEX and 184.80 ± 13.87% for 1h+DEX), morphology, and SOD activity (77.33 ± 3.35 OD for 1d+DEX; 76.87 ± 3.59 OD for 1h+DEX at 1 h), while reducing ROS levels (2417.33 ± 345.49 RFU for 1d+DEX and 1843.00 ± 98.53 RFU at 4 h), especially in hOBs. The co-treatment of RSV or derivatives with DEX restored the expression of genes that were downregulated by DEX, such as HO-1 (1.76 ± 0.05 for 1d+DEX and 1.79 ± 0.01 for 1h+DEX), CAT (0.97 ± 0.06 for 1d+DEX and 0.99 ± 0.03 for 1h+DEX), NRF2 (1.62 ± 0.04 for 1d+DEX and 1.91 ± 0.05 for 1h+DEX), SOD1 (1.63 ± 0.15 for 1d+DEX and 1.69 ± 0.04 for 1h+DEX). In addition, 1d and 1h preserved collagen production (111.79 ± 1.56 for 1d+DEX and 122.27 ± 1.56 for 1h+DEX). In conclusion, this study suggests that the RSV derivatives 1d and 1h hold promise as potential antioxidant agents to counteract DEX-induced oxidative stress. These findings contribute to the development of novel therapeutic strategies for managing oxidative stress-related oral conditions.

Therapeutic Applications of Resveratrol in Hepatic Encephalopathy through Its Regulation of the Microbiota, Brain Edema, and Inflammation

Hepatic encephalopathy is a common complication in patients with liver cirrhosis and portosystemic shunting. Patients with hepatic encephalopathy present a variety of clinical features, including neuropsychiatric manifestations, cognitive dysfunction, impaired gut barrier function, hyperammonemia, and chronic neuroinflammation. These pathogeneses have been linked to various factors, including ammonia-induced oxidative stress, neuronal cell death, alterations in the gut microbiome, astrocyte swelling, and blood-brain barrier disruptions. Many researchers have focused on identifying novel therapeutics and prebiotics in the hope of improving the treatment of these conditions. Resveratrol is a natural polyphenic compound and is known to exert several pharmacological effects, including antioxidant, anti-inflammatory, and neuroprotective activities. Recent studies suggest that resveratrol contributes to improving the neuropathogenic effects of liver failure. Here, we review the current evidence describing resveratrol's effects in neuropathogenesis and its impact on the gut-liver axis relating to hepatic encephalopathy. We highlight the hypothesis that resveratrol exerts diverse effects in hepatic encephalopathy and suggest that these effects are likely mediated by changes to the gut microbiota, brain edema, and neuroinflammation.

Towards resolving the enigma of the dichotomy of resveratrol: cis- and trans-resveratrol have opposite effects on TyrRS-regulated PARP1 activation

Unlike widely perceived, resveratrol (RSV) decreased the average lifespan and extended only the replicative lifespan in yeast. Similarly, although not widely discussed, RSV is also known to evoke neurite degeneration, kidney toxicity, atherosclerosis, premature senescence, and genotoxicity through yet unknown mechanisms. Nevertheless, in vivo animal models of diseases and human clinical trials demonstrate inconsistent protective and beneficial effects. Therefore, the mechanism of action of RSV that elicits beneficial effects remains an enigma. In a previously published work, we demonstrated structural similarities between RSV and tyrosine amino acid. RSV acts as a tyrosine antagonist and competes with it to bind to human tyrosyl-tRNA synthetase (TyrRS). Interestingly, although both isomers of RSV bind to TyrRS, only the cis-isomer evokes a unique structural change at the active site to promote its interaction with poly-ADP-ribose polymerase 1 (PARP1), a major determinant of cellular NAD+-dependent stress response. However, retention of trans-RSV in the active site of TyrRS mimics its tyrosine-bound conformation that inhibits the auto-poly-ADP-ribos(PAR)ylation of PARP1. Therefore, we proposed that cis-RSV-induced TyrRS-regulated auto-PARylation of PARP1 would contribute, at least in part, to the reported health benefits of RSV through the induction of protective stress response. This observation suggested that trans-RSV would inhibit TyrRS/PARP1-mediated protective stress response and would instead elicit an opposite effect compared to cis-RSV. Interestingly, most recent studies also confirmed the conversion of trans-RSV and its metabolites to cis-RSV in the physiological context. Therefore, the finding that cis-RSV and trans-RSV induce two distinct conformations of TyrRS with opposite effects on the auto-PARylation of PARP1 provides a potential molecular basis for the observed dichotomic effects of RSV under different experimental paradigms. However, the fact that natural RSV exists as a diastereomeric mixture of its cis and trans isomers and cis-RSV is also a physiologically relevant isoform has not yet gained much scientific attention.

Resveratrol increases the activation markers and changes the release of inflammatory cytokines of hepatic stellate cells

The phytoalexin Resveratrol (3,5,4'-trihydroxystilbene; RSV) has been related to numerous beneficial effects on health by its cytoprotection and chemoprevention activities. Liver fibrosis is characterized by the extracellular matrix accumulation after hepatic injury and can lead to cirrhosis. Hepatic stellate cells (HSC) play a crucial role during fibrogenesis and liver wound healing by changing their quiescent phenotype to an activated phenotype for protecting healthy areas from damaged areas. Strategies on promoting the activated HSC death, the quiescence return or the cellular activation stimuli decrease play an important role on reducing liver fibrosis. Here, we evaluated the RSV effects on some markers of activation in GRX, an HSC model. We further evaluated the RSV influence in the ability of GRX on releasing inflammatory mediators. RSV at 1 and 10 µM did not alter the protein content of α-SMA, collagen I and GFAP; but 50 µM increased the content of these activation-related proteins. Also, RSV did not change the myofibroblast-like morphology of GRX. Interestingly, RSV at 10 and 50 µM decreased the GRX migration and collagen-I gel contraction. Finally, we showed that RSV triggered the increase in the TNF-α and IL-10 content in culture media of GRX while the opposite occurred for the IL-6 content. Altogether, these results suggested that RSV did not decrease the activation state of GRX and oppositely, triggered a pro-activation effect at the 50 µM concentration. However, despite the increase of TNF- α in culture media, these results on IL-6 and IL-10 secretion were in accordance with the anti-inflammatory role of RSV in our model.

Resveratrol Inhibits Particulate Matter-Induced Inflammatory Responses in Human Keratinocytes

Particulate matter (PM), a major air pollutant, is a complex mixture of solid and liquid particles of various sizes. PM has been demonstrated to cause intracellular inflammation in human keratinocytes, and is associated with various skin disorders, including atopic dermatitis, eczema, and skin aging. Resveratrol is a natural polyphenol with strong antioxidant properties, and its beneficial effects against skin changes due to PM remain elusive. Therefore, in the present study, we investigated the effect of resveratrol on PM-induced skin inflammation and attempted to deduce the molecular mechanisms underlying resveratrol’s effects. We found that resveratrol inhibited PM-induced aryl hydrocarbon receptor activation and reactive oxygen species formation in keratinocytes. It also suppressed the subsequent cellular inflammatory response by inhibiting mitogen-activated protein kinase activation. Consequentially, resveratrol reduced PM-induced cyclooxygenase-2/prostaglandin E2 and proinflammatory cytokine expression, including that of matrix metalloproteinase (MMP)-1, MMP-9, and interleukin-8, all of which are known to be central mediators of various inflammatory conditions and aging. In conclusion, resveratrol inhibits the PM-induced inflammatory response in human keratinocytes, and we suggest that resveratrol may have potential for preventing air pollution-related skin problems.

Potential Adverse Effects of Resveratrol: A Literature Review

Due to its health benefits, resveratrol (RE) is one of the most researched natural polyphenols. Resveratrol's health benefits were first highlighted in the early 1990s in the French paradox study, which opened extensive research activity into this compound. Ever since, several pharmacological activities including antioxidant, anti-aging, anti-inflammatory, anti-cancerous, anti-diabetic, cardioprotective, and neuroprotective properties, were attributed to RE. However, results from the available human clinical trials were controversial concerning the protective effects of RE against diseases and their sequelae. The reason for these conflicting findings is varied but differences in the characteristics of the enrolled patients, RE doses used, and duration of RE supplementation were proposed, at least in part, as possible causes. In particular, the optimal RE dosage capable of maximizing its health benefits without raising toxicity issues remains an area of extensive research. In this context, while there is a consistent body of literature on the protective effects of RE against diseases, there are relatively few reports investigating its possible toxicity. Indeed, toxicity and adverse effects were reported following consumption of RE; therefore, extensive future studies on the long-term effects, as well as the in vivo adverse effects, of RE supplementation in humans are needed. Furthermore, data on the interactions of RE when combined with other therapies are still lacking, as well as results related to its absorption and bioavailability in the human body. In this review, we collect and summarize the available literature about RE toxicity and side effects. In this process, we analyze in vitro and in vivo studies that have addressed this stilbenoid. These studies suggest that RE still has an unexplored side. Finally, we discuss the new delivery methods that are being employed to overcome the low bioavailability of RE.

The Involvement of SDF-1α/CXCR4 Axis in Radiation-Induced Acute Injury and Fibrosis of Skin

Radiation-induced acute skin injury and consequent fibrosis are common complications of cancer radiotherapy and radiation accidents. Stromal cell-derived factor-1α (SDF-1α) and its receptor, CXC chemokine receptor 4 (CXCR4) have been shown to be involved in multiple cellular events. However, the role of SDF-1α/CXCR4 axis in radiation-induced acute injury and fibrosis of skin has not been reported. In this study, we found that the expression of SDF-1α and CXCR4 was significantly increased in irradiated skin tissues of humans, monkeys and rats, compared to their nonirradiated counterparts. Mice with keratinocyte-specific ablation of CXCR4 showed less severe skin damage than wild-type mice after receiving a 35 Gy dose of radiation. Consistently, subcutaneous injection of AMD3100, an FDA approved SDF-1α/CXCR4 inhibitor, attenuated skin injury and fibrosis induced by exposure to radiation in a rat model. Mechanically, the SDF-1α/CXCR4 axis promotes pro-fibrotic TGF-b/Smad signaling through the PI3K-MAPK signaling cascade in human keratinocyte HaCaT cells and skin fibroblast WS1 cells. AMD3100 inhibited Smad2 nuclear translocation and transcriptional activity of Smad2/3 induced by radiation, which suppressed the pro-fibrotic TGF-b/Smad signaling pathway activated by exposure. Taken together, these findings demonstrate the involvement of SDF-1α/CXCR4 axis in radiation-induced acute injury and fibrosis of skin, and indicate that AMD3100 would be an effective countermeasure against these diseases.

Natural compounds in the chemoprevention of alcoholic liver disease

Alcoholic liver disease (ALD), caused by excessive consumption of alcohol, is a major cause of chronic liver disease worldwide. Much effort has been expended to explore the pathogenesis of ALD. Hepatic cell injury, oxidative stress, inflammation, regeneration, and bacterial translocation are all involved in the pathogenesis of ALD. Immediate abstinence is the most important therapeutic treatment for affected individuals. However, the medical treatment for ALD had not advanced in a long period. Intriguingly, an increasing body of research indicates the potential of natural compounds in the targeted therapy of ALD. A plethora of dietary natural products such as flavonoids, resveratrol, saponins, and β-carotene are found to exert protective effects on ALD. This occurs through various mechanisms composed of antioxidative, anti-inflammatory, iron chelation, pro-apoptosis, and/or antiproliferation of hepatic stellate cells and hepatocellular carcinoma cells. In this review, we will summarize current knowledge about the pathogenesis and treatments of ALD and focus on the potential of natural compounds in ALD therapies and underlying mechanisms.

3,5-Diethoxy-3'-Hydroxyresveratrol (DEHR) Ameliorates Liver Fibrosis via Caveolin-1 Activation in Hepatic Stellate Cells and in a Mouse Model of Bile Duct Ligation Injury

Hepatic stellate cells (HSCs) are involved in the pathogenesis of liver fibrosis. Resveratrol, 3,5,4′-trihydroxystilbene, is a dietary polyphenol found in natural food products. Here, we evaluated the anti-proliferative effects of a synthetic resveratrol derivative, 3,5-diethoxy-3′-hydroxyresveratrol (DEHR), on HSCs. Flow cytometry and Western blot analyses showed that DEHR induces apoptosis through the upregulation of cleaved caspase-3 and poly (ADP-ribose) polymerase expression and reduction in the level of an anti-apoptotic protein B-cell lymphoma 2 (Bcl2). As caveolin-1 (CAV1), a competitive inhibitor of heme oxygenase 1 (HO-1), is related to apoptotic proteins in hepatic cells, we focused on the role of CAV1 in DEHR-induced apoptosis in HSCs through Western blot analyses. Our results showed that the inhibitory effect of DEHR on cell viability was stronger in HO-1 siRNA-transfected cells but weakened in CAV1 siRNA-transfected cells. Collagen concentration was significantly reduced, whereas CAV1 expression increased after treatment of a bile duct ligation injury-induced liver fibrosis model with DEHR for four weeks. We confirmed that DEHR treatment significantly reduced fibrous hyperplasia around the central veins, using hematoxylin and eosin and Sirius red staining. DEHR ameliorates liver fibrosis in vitro and in vivo, possibly through a mechanism involving CAV1.

Effects of resveratrol on activation of NLRP3 inflammasome in HSC-T6 cells

AIM

To investigate the effect of resveratrol (Res) on the activation of nod-like receptor protein 3 (NLRP3) inflammasome in hepatic stellate cell (HSC)-T6 cells and to explore the anti-fibrotic mechanism of Res.

METHODS

Rat hepatic stellate cell (HSC) line HSC-T6 was used. HSC-T6 cells were seeded into cell culture plates with high glucose DMEM medium containing 10% fetal bovine serum for 24 h. Then, the cells were incubated with Res (4, 8, and 16 μmol/L) or acetylcysteine (NAC; 5 mmol/L) for 24 h. Oxidative stress (OS) was induced by exposure to hydrogen peroxide (H₂O₂; 0.2 mmol/L) for 4 h. MTT method was used to observe the effect of Res on HSC-T6 cell proliferation. ELISA was used to detect the contents of type I collagen (COL-I), transforming growth factor β1 (TGF-β1), interleukin (IL)-1β, IL-18, malondialdehyde (MDA), and superoxide dismutase (SOD) in cell culture supernatant. Reactive oxygen species (ROS) production was measured with a fluorescence microplate reader following staining with DCFH-DA probe. Western blot analysis was used to detect the expression of alpha-smooth muscle actin (α-SMA), NLRP3, apoptosis-associated speck-like protein (ASC), and cysteinyl aspartate specific proteinase 1 (caspase 1) in HSC-T6 cells.

RESULTS

Compared with control cells, Res at concentrations from 4 μmol/L to 64 μmol/L significantly suppressed the proliferation of HSC-T6 cells. Compared with control cells, OS induction significantly increased the proliferation of HSC-T6 cells, the contents of COL-1, TGF-β1, MDA, IL-1β, and IL-18 in cell culture supernatant, intracellular ROS production, and the protein expression of α-SMA, NLRP3, ASC, and caspase 1-p10 (P < 0.01), but decreased the content of SOD in cell culture supernatant (P < 0.01). Compared with the OS group, treatment with low-, medium-, or high-dose Res or positive control NAC significantly decreased the proliferation of HSC-T6 cells, the contents of COL-1, TGF-β1, MDA, IL-1β, and IL-18 in cell culture supernatant, intracellcular ROS production, and the protein expression of α-SMA, NLRP3, ASC, and caspase 1-p10 (P < 0.01), but increased the content of SOD in cell culture supernatant (P < 0.01).

CONCLUSION

Res could suppress the proliferation and activation of HSC-T6 cells via down-regulation of ROS-NLRP3 inflammasome signaling.

Autophagy induced by purple pitanga (Eugenia uniflora L.) extract triggered a cooperative effect on inducing the hepatic stellate cell death

Activated hepatic stellate cells (HSC) are the major source of collagen I in liver fibrosis. Eugenia uniflora L. is a tree species that is widely distributed in South America. E. uniflora L. fruit-popularly known as pitanga-has been shown to exert beneficial properties. Autophagy contributes to the maintenance of cellular homeostasis and survival under stress situation, but it has also been suggested to be an alternative cell death pathway. Mitochondria play a pivotal role on signaling cell death. Mitophagy of damaged mitochondria is an important cell defense mechanism against organelle-mediated cell death signaling. We previously found that purple pitanga extract induced mitochondrial dysfunction, cell cycle arrest, and death by apoptosis and necrosis in GRX cells, a well-established activated HSC line. We evaluated the effects of 72-h treatment with crescent concentrations of purple pitanga extract (5 to 100 μg/mL) on triggering autophagy in GRX cells, as this is an important mechanism to cells under cytotoxic conditions. We found that all treated cells presented an increase in the mRNA expression of autophagy-related protein 7 (ATG7). Concomitantly, flow cytometry and ultrastructural analysis of treated cells revealed an increase of autophagosomes/autolysosomes that consequentially led to an increased mitophagy. As purple pitanga extract was previously found to be broadly cytotoxic to GRX cells, we postulated that autophagy contributes to this scenario, where cell death seems to be an inevitable fate. Altogether, the effectiveness on inducing activated HSC death can make purple pitanga extract a good candidate on treating liver fibrosis.

Resveratrol Regulates the Quiescence-Like Induction of Activated Stellate Cells by Modulating the PPARγ/SIRT1 Ratio

The activation of hepatic stellate cell (HSC), from a quiescent cell featuring cytoplasmic lipid droplets to a proliferative myofibroblast, plays an important role in liver fibrosis development. The GRX line is an activated HSC model that can be induced by all-trans-retinol to accumulate lipid droplets. Resveratrol is known for activating Sirtuin1 (SIRT1), a NAD(+)-dependent deacetylase that suppresses the activity of peroxisome proliferator-activated receptor gamma (PPARγ), an important adipogenic transcription factor involved in the quiescence maintenance of HSC. We evaluated the effects of 0.1 μM of resveratrol in retinol-induced GRX quiescence by investigating the interference of SIRT1 and PPARγ on cell lipogenesis. GRX lipid accumulation was evaluated through Oil-red O staining, triacylglycerides quantification, and [(14)C] acetate incorporation into lipids. mRNA expression and protein content of SIRT1 and PPARγ were measured by RT-PCR and immunoblotting, respectively. Resveratrol-mediated SIRT1 stimuli did not induce lipogenesis and reduced the retinol-mediated fat-storing capacity in GRX. In order to support our results, we established a cell culture model of transgenic super expression of PPARγ in GRX cells (GRXPγ). Resveratrol reduced lipid droplets accumulation in GRXPγ cells. These results suggest that the PPARγ/SIRT1 ratio plays an important role in the fate of HSC. Thus, whenever the PPARγ activity is greater than SIRT1 activity the lipogenesis is enabled.

The interplay between apoptosis, mitophagy and mitochondrial biogenesis induced by resveratrol can determine activated hepatic stellate cells death or survival

Resveratrol has been the focus of numerous studies reporting opposite effects that depend on its concentration. The GRX is an activated hepatic stellate cells model used to study liver fibrosis development and resolution. We recently showed that GRX treatment with RSV (0.1-50 µM) for 24 h triggered dose-dependent pro-oxidant effects, resulting in cytotoxicity and cell damage only at the highest concentration. Here, we evaluated whether the pro-oxidant effect of resveratrol treatment is accompanied by alterations on the GRX mitochondrial metabolism, and whether the concomitantly autophagy/mitophagy induction can influence on cell death or survival. We demonstrated that all concentrations of resveratrol promoted an increase of GRX cell death signals, altering the mitochondrial dynamics and function. Cells treated with all resveratrol concentrations presented higher autophagy/mitophagy features, but only treatments with 1 and 10 µM of resveratrol-induced mitochondrial biogenesis. Since cell damage was higher and there was no mitochondrial biogenesis in GRX treated with 50 µM of resveratrol, we suggest that these cells failed to remove and replace all damaged mitochondria. In conclusion, the cytotoxic effect of resveratrol that effectively promotes cell death could be related to the interrelation between the concomitant induction of apoptosis, autophagy/mitophagy and mitochondrial biogenesis in GRX.

Ovarian actions of resveratrol

Resveratrol, a natural polyphenol found in grapes, berries, and medicinal plants, exhibits antioxidant and anti-inflammatory activities and has been proposed to be a longevity-prolonging agent. There is also growing evidence that resveratrol has cardioprotective properties and beneficial effects on both glucose and lipid metabolism. Recently, several studies have examined the use of resveratrol as a therapeutic agent to treat numerous pathological and metabolic disorders. Herein, we present insights into the mechanisms of action, biological effects, and current evidence of actions of resveratrol on the ovary. In vitro, resveratrol inhibits proliferation and androgen production by theca-interstitial cells. Resveratrol also exerts a cytostatic, but not cytotoxic, effect on granulosa cells, while decreasing aromatization and vascular endothelial growth factor expression. In vivo, resveratrol treatment reduced the size of adipocytes and improved estrus cyclicity in the previously acyclic rat model of polycystic ovary syndrome (PCOS). In addition, resveratrol increased the ovarian follicular reserve and prolonged the ovarian life span in rats. Taken together, resveratrol emerges as a potential therapeutic agent to treat conditions associated with androgen excess, such as PCOS. The efficacy of resveratrol in the treatment of gynecological conditions requires further investigation.

Resveratrol and liver: A systematic review

Background:

Recent studies demonstrated that resveratrol has many therapeutic effects on liver disorders. Resveratrol significantly increased survival after liver transplantation, decreased fat deposition, necrosis, and apoptosis which induced by ischemia in Wistar rats. It provided liver protection against chemical, cholestatic, and alcohol injury. Resveratrol can improve glucose metabolism and lipid profile and decrease liver fibrosis and steatosis. Furthermore, it was able to alter hepatic cell fatty acid composition. According to extension of liver disease around the world and necessity of finding new threat, this review critically examines the current preclinical in vitro and in vivo studies on the preventive and therapeutic effects of resveratrol in liver disorders.

Materials and Methods:

A search in PubMed, Google Scholar, and Scopus was undertaken to identify relevant literature using search terms, including “liver,” “hepatic,” and “Resveratrol.” Both in vivo and in vitro studies were included. No time limiting considered for this search.

Results:

A total of 76 articles were eligible for this review. In these articles, resveratrol shows antioxidative properties in different models of hepatitis resulting in reducing of hepatic fibrosis.

Conclusion:

Resveratrol could reduce hepatic steatosis through modulating the insulin resistance and lipid profile in animals. These high quality preclinical studies propose the potential therapeutic implication of resveratrol in liver disorders especially those with hepatic steatosis. Resveratrol can play a pivotal role in prevention and treatment of liver disorders by reducing hepatic fibrosis.

Dual effect of red wine on liver redox status: a concise and mechanistic review

Chronic ethanol consumption is a strong risk factor for the development of liver disease. Multiple mechanisms are involved in ethanol-mediated liver injury; oxidative stress being pointed has an important factor. However, it should be noted that moderate consumption of red wine has been associated with hepatoprotective effects, mainly due to the antioxidant effect of resveratrol, one of its polyphenolic compounds. In this paper, the potential molecular mechanisms through which the protective effects of resveratrol counteract the oxidative effect of ethanol and the way as this dual effect impacts liver oxidative stress are reviewed. Mechanistic evaluation of modulation of oxidative signaling pathways by ethanol and resveratrol may explain the pathogenesis of various liver diseases and ultimately to disclose possible pharmacological therapies.

Capsaicin modulates proliferation, migration, and activation of hepatic stellate cells

Capsaicin, the active component of chili pepper, has been reported to have antiproliferative and anti-inflammatory effects on a variety of cell lines. In the current study, we aimed to investigate the effects of capsaicin during HSC activation and maintenance. Activated and freshly isolated HSCs were treated with capsaicin. Proliferation was measured by incorporation of EdU. Cell cycle arrest and apoptosis were investigated using flow cytometry. The migratory response to chemotactic stimuli was evaluated by a modified Boyden chamber assay. Activation markers and inflammatory cytokines were determined by qPCR, immunocytochemistry, and flow cytometry. Our results show that capsaicin reduces HSC proliferation, migration, and expression of profibrogenic markers of activated and primary mouse HSCs. In conclusion, the present study shows that capsaicin modulates proliferation, migration, and activation of HSC in vitro.

Effects of resveratrol in experimental and clinical non-alcoholic fatty liver disease

The prevalence of obesity and related conditions like non-alcoholic fatty liver disease (NAFLD) is increasing worldwide and therapeutic options are limited. Alternative treatment options are therefore intensively sought after. An interesting candidate is the natural polyphenol resveratrol (RSV) that activates adenosinmonophosphate-activated protein kinase (AMPK) and silent information regulation-2 homolog 1 (SIRT1). In addition, RSV has known anti-oxidant and anti-inflammatory effects. Here, we review the current evidence for RSV-mediated effects on NAFLD and address the different aspects of NAFLD and non-alcoholic steatohepatitis (NASH) pathogenesis with respect to free fatty acid (FFA) flux from adipose tissue, hepatic de novo lipogenesis, inadequate FFA β-oxidation and additional intra- and extrahepatic inflammatory and oxidant hits. We review the in vivo evidence from animal studies and clinical trials. The abundance of animal studies reports a decrease in hepatic triglyceride accumulation, liver weight and a general improvement in histological fatty liver changes, along with a reduction in circulating insulin, glucose and lipid levels. Some studies document AMPK or SIRT1 activation, and modulation of relevant markers of hepatic lipogenesis, inflammation and oxidation status. However, AMPK/SIRT1-independent actions are also likely. Clinical trials are scarce and have primarily been performed with a focus on overweight/obese participants without a focus on NAFLD/NASH and histological liver changes. Future clinical studies with appropriate design are needed to clarify the true impact of RSV treatment in NAFLD/NASH patients.

Cytotoxic effect of amphotericin B in a myofibroblast cell line

In this study we investigate whether Amphotericin B (AmB), a widely used antifungal agent, could decrease the proliferation of a myofibroblast cell line - GRX, a model of activated hepatic stellate cells (HSC). Three different hepatic cell lines (GRX, Hep G2 and ARL-6) were treated with two concentrations of AmB (1.25 μg/mL or 2.50 μg/mL). Cytotoxicity was assessed by MTT assay. The effects of AmB on GRX migration was evaluated by Wound-healing Assay. Cell cycle arrest was investigated by flow cytometry. Apoptosis and autophagy were analyzed by Caspase 3 and LC3 immunostaining, respectively. Treatment with AmB 1.25 or 2.50 μg/mL showed a decrease in viability of GRX cells. This decrease was not observed for Hep G2 or ARL-6 in any of the two AmB concentrations tested. GRX cells treated with 1.25 μg/mL AmB were unable to close the wound after 96 h. Cell cycle analysis showed an increase in sub-G1 population and a decrease in G2/M population in AmB-treated cells. In addition, AmB-treated GRX cells showed increased expression of LC-3 and Caspase-3 by immunohistochemistry, suggesting an increase in both autophagy and apoptosis. Here we show that AmB is cytotoxic for GRX cells, a model of activated HSC, but not for hepatic lineages HepG2 and ARL6.

Capsaicin induces de-differentiation of activated hepatic stellate cell

Hepatic stellate cells (HSC) play a key role in liver fibrogenesis. Activation of PPARγ and inhibition of fibrogenic molecules are potential strategies to block HSC activation and differentiation. A number of natural products have been suggested to have antifibrotic effects for the de-activation and de-differentiation of HSCs. The purpose of this study was to investigate the in vitro effects of capsaicin on HSC de-activation and de-differentiation. The results demonstrated that capsaicin induced quiescent phenotype in GRX via PPARγ activation. Significant decrease in COX-2 and type I collagen mRNA expression was observed in the first 24 h of treatment. These events preceded the reduction of TGF-β1 and total collagen secretion. Thus, capsaicin promoted down-regulation of HSC activation by its antifibrotic and anti-inflammatory actions. These findings demonstrate that capsaicin may have potential as a novel therapeutic agent for the treatment of liver fibrosis.

Antiproliferative effect of catechin in GRX cells

The phenolic compounds present in cocoa seeds have been studied regarding health benefits, such as antioxidant and anti-inflammatory activities. Fibrosis is a wound healing response that occurs in almost all patients with chronic liver injury. A large number of cytokines and soluble intercellular mediators are related to changes in the behavior and phenotype of the hepatic stellate cell (HSC) that develop a fibrogenic and contractile phenotype leading to the development of fibrosis. The objective of this study was to assess the catechin effect in GRX liver cells in activities such as cell growth and inflammation. The GRX cells treatment with catechin induced a significant decrease in cell growth. This mechanism does not occur by apoptosis or even by autophagy because there were no alterations in expression of caspase 3 and PARP (apoptosis), and LC3 (autophagy). The expression of p27 and p53 proteins, regulators of the cell cycle, showed increased expression, while COX-2 and IL-6 mRNA showed a significant decrease in expression. This study shows that catechin decreases cell growth in GRX cells and, probably, this decrease does not occur by apoptosis or autophagy but through an anti-inflammatory effect and cell cycle arrest. Catechin also significantly decreased the production of TGF-β by GRX cells, showing a significant antifibrotic effect.

The protective role of natural phytoalexin resveratrol on inflammation, fibrosis and regeneration in cholestatic liver injury

Liver injuries can trigger a cascade of inflammatory responses and as a result, initiate the process of hepatic regeneration and fibrogenesis. Resveratrol (RSV) has multiple health-promoting benefits. This study evaluated the potential protective effects and mechanism of RSV as related to cholestatic liver injury. RSV was given (4 mg/kg/day, i.p.) for either 3 days or 7 days after bile duct ligation (BDL) injury. RSV significantly reduced serum ALT, AST but not T-bil on Day 3. At this early stage of injury, RSV significantly reduced TNF-α and IL-6 mRNA and decreased the number of Kupffer cells (CD68(+) ) recruited in the injured liver. RSV decreased hepatic fibrosis and reduced collagen Iα1 and TIMP-1 mRNA on Day 7. At the later stages of injury, RSV increased the number of Ki67(+) hepatocytes indicating that RSV promoted hepatocyte proliferation. Additionally, it resulted in decreased expression of 4-hydroxynonenal and increased expression of the hepatocyte growth factor protein and mRNA in the RSV-treated BDL group. Meanwhile, RSV reduced the mortality rate of BDL mice. In conclusion, RSV attenuated inflammation and reduced Kupffer cells activation. RSV decreased fibrosis and promoted hepatocyte regeneration, which increased the survival of BDL mice. RSV was beneficial for the treatment of cholestatic liver injury.

Icaritin induces cell death in activated hepatic stellate cells through mitochondrial activated apoptosis and ameliorates the development of liver fibrosis in rats

AIM OF THE STUDY

Icaritin is an active ingredient extracted from the plant Herba Epimedium Sagittatum (Sieb. et Zucc.) Maxim. The purpose of this study is to investigate the effects and mechanisms of icaritin-induced cell death in activated hepatic stellate cells (HSCs) and ameliorating the development of liver fibrosis in rats.

MATERIALS AND METHODS

: In vitro, icaritin-induced cell death rates in HSC-T6 (rat) and LX-2 (human) HSC lines as well as normal hepatocyte cell lines HL-7702 (L02) and WRL-68 were assayed by MTT method, and the apoptotic ratios were detected by both flow cytometry and the Annexin-V-FITC Apoptosis Detection Kit. A Whole Rat Genome Microarray Kit was used to identify expression of interest genes through fold-change screening. In vivo study, experimental liver fibrosis models were built by carbon tetrachloride (CCl(4)) or common bile duct ligation (CBDL) in Wistar rats. Icaritin (1mg/kg/day, three days a week) was administered by gastric gavage for four weeks (n=6 per group). At the end of the study, serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT) as well as the contents of hydroxyproline and collagen I in liver tissues were measured. Histopathological changes and the distribution of activated HSCs were observed in the liver tissues using hematoxyline-eosin (HE) staining and immunohistochemical staining for α-smooth muscle actin (α-SMA).

RESULTS

Icaritin induced apoptosis in HSC-T6 and LX-2 in a concentration- and time-dependent manner with little toxicity to normal hepatocyte cell lines. The IC(50) of icaritin in HSC-T6 was 12.83 μM at 48 h. Apoptotic ratio of HSC-T6 treated with 24 μM icaritin was 20.19%, and the G2 phase of the cell cycle did not occur (P<0.05). Gene analysis showed that icaritin up-regulated Bak-1, Bmf and Bax expression while significantly down-regulated Bcl-2 expression (vs. control group, P<0.01). These results suggested that mitochondrial pathway played an important role in icaritin-induced apoptosis in activated HSCs. In vivo results showed that icaritin reduced the number of activated HSCs, and brought the elevated levels of AST, ALT, hydroxyproline and collagen I to normal or near normal values (vs. model group, P<0.05).

CONCLUSIONS

Icaritin can induce cell death in activated HSCs through mitochondria-mediated apoptosis, ameliorate the progression of hepatic fibrosis in rats, and could be a promising drug for treating liver fibrosis.

Resveratrol and liver disease: from bench to bedside and community

Liver diseases incorporate several maladies, which can range from benign histological changes to serious life-threatening conditions. These may include inborn metabolic disease, primary and metastatic cancers, alcoholic cirrhosis, viral hepatitis and drug-induced hepatotoxicity. Liver disease remains a major cause of morbidity and mortality with significant economic and social costs. Several novel approaches are currently being studied which may provide a better therapeutic outcome. The use of naturally occurring phytochemicals, some of them obtained from dietary sources, in the amelioration of illness have recently gained considerable popularity. These agents, having anti-oxidant and anti-inflammatory properties, provide a safe and effective means of ameliorating chronic disease. Resveratrol, a grape polyphenol, has shown considerable promise as a therapeutic agent in the treatment of the aforementioned liver ailments. Several studies have highlighted the hepatoprotective properties of resveratrol. Resveratrol has been shown to prevent hepatic damage because of free radicals and inflammatory cytokines, induce anti-oxidant enzymes and elevate glutathione content. Resveratrol has also been shown to modulate varied signal transduction pathways implicated in liver diseases. This review critically examines the current preclinical in vitro and in vivo studies on the preventive and therapeutic effects of resveratrol in liver diseases. The review highlights the pharmacological mechanisms involved in mediating the aforementioned effects. Toxicity, pharmacokinetics and clinical bioavailability of resveratrol are also reviewed in this article. The challenges involved, future directions and novel approaches such as site-specific drug delivery in the use of resveratrol for the prevention and treatment of liver disease are also discussed.

Thiol redox systems and protein kinases in hepatic stellate cell regulatory processes

Hepatic stellate cells (HSC) are the major producers of collagen in the liver and their conversion from resting cells to a proliferating, contractile and fibrogenic phenotype ('activation') is a critical step, leading to liver fibrosis characterized by deposition of excessive extracellular matrix. Cytokines, growth factors, reactive oxygen and nitrogen species (ROS/RNS), lipid peroxides and their products deriving from hepatocytes, Kupffer cells and other cells converge on HSC and influence their activation. This review focuses on glutathione and thioredoxin pathways, with particular emphasis on their role in HSC. These two systems have been shown to act in the metabolism of hydrogen peroxide, control of thiol redox balance and regulation of signalling pathways. Particular attention is paid to mitochondria and NADPH oxidase. Detailed knowledge of specific signalling, redox conditions and apoptotic processes will be of help in devising proper pharmacological treatments for liver fibrosis.

An antioxidant resveratrol significantly enhanced replication of hepatitis C virus

AIM: To elucidate the effect of antioxidants, resveratrol (RVT) and astaxanthin (AXN), on hepatitis C virus (HCV) replication.

METHODS: We investigated the effect of recent popular antioxidant supplements on replication of the HCV replicon system OR6. RVT is a strong antioxidant and a kind of polyphenol that inhibits replication of various viruses. AXN is also a strong antioxidant. The replication of HCV RNA was assessed by the luciferase reporter assay. An additive effect of antioxidants on antiviral effects of interferon (IFN) and ribavirin (RBV) was investigated.

RESULTS: This is the first report to investigate the effect of RVT and AXN on HCV replication. In contrast to other reported viruses, RVT significantly enhanced HCV RNA replication. Vitamin E also enhanced HCV RNA replication as reported previously, although AXN didnot affect replication. IFN and RBV significantly reduced HCV RNA replication, but these effects were dose-dependently hampered and attenuated by the addition of RVT. AXN didnot affect antiviral effects of IFN or RBV.

CONCLUSION: These results suggested that RVT is not suitable as an antioxidant therapy for chronic hepatitis C.

Effects of resveratrol on proliferation and apoptosis in rat ovarian theca-interstitial cells

Polycystic ovary syndrome (PCOS) is characterized by ovarian dysfunction and associated with ovarian theca-interstitial (T-I) cell hyperplasia, hyperinsulinemia, systemic inflammation and oxidative stress. This in vitro study tested whether rat T-I cell growth with or without insulin can be altered by resveratrol, a natural polyphenol with anti-carcinogenic, anti-inflammatory, anti-proliferative and antioxidant properties. Rat T-I cells were cultured with and without resveratrol and/or insulin, and the effects on DNA synthesis, number of viable cells and markers of apoptosis were evaluated. Resveratrol alone induced a potent concentration-dependent inhibition of cell growth by inhibiting DNA synthesis, decreasing the number of viable cells and increasing the activity of executioner caspases 3 and 7; these effects of resveratrol counteracted the pro-proliferative and anti-apoptotic effects of insulin. Immunofluorescence analysis of cells incubated with resveratrol showed concentration- and time-dependent morphological changes consistent with apoptosis. The present findings indicate that resveratrol promotes apoptosis to reduce rat T-I cell growth in vitro as well as inhibiting insulin-induced rat T-I cell growth. This suggests a possibility that resveratrol and/or mechanisms mediating its effect may be relevant to the development of novel treatments for PCOS, which is characterized by both excessive ovarian mesenchyma growth and hyperinsulinemia.

Protective and therapeutic effects of resveratrol on acetic acid-induced gastric ulcer

Sprague Dawley rats of both sexes were injected with either saline or RVT (10 mg/kg) either before or after acetic acid ulcer induction and decapitated 3, 5 or 10 days after ulcer. In the saline-treated ulcer groups, macroscopically evident ulcers were observed, while RVT-pretreated or RVT-treated groups had lower macroscopic ulcer scores. Likewise, the microscopic damage scores were lower for the RVT-administered groups. Gastric myeloperoxidase activity, malondialdehyde, collagen and tumour necrosis factor-alpha levels, as well as luminol- and lucigenin-enhanced chemiluminescence levels that were elevated in the saline-administered ulcer groups, were depressed with both RVT-pretreatment and RVT-treatment. Moreover, depleted glutathione levels in the ulcer groups were increased back to control levels by both pre- and post-treatments of RVT. Results demonstrate that resveratrol has both protective and therapeutic effects on oxidative gastric damage by suppressing pro-inflammatory cascades, including the activation of pro-inflammatory cytokines, accumulation of neutrophils and release of oxygen-derived free radicals.

Resveratrol amplifies profibrogenic effects of free fatty acids on human hepatic stellate cells

AIM

To ascertain whether resveratrol affects the expression of free fatty acids (FFA)-induced profibrogenic genes, death receptors, and/or apoptosis-related molecules in human hepatic stellate cells, using the LX-2 cell line.

METHODS

Cells were cultured in the presence of FFAs (2:1 oleate : palmitate) and subsequently treated with resveratrol. Gene expression rates were determined by quantitative real-time PCR. The 50% lethal dose (LD(50)) of resveratrol in the presence of FFAs was assessed with the MTT viability test.

RESULTS

Compared to vehicle controls, incubation of LX-2 cells with 0.5 mM FFAs induced profibrogenic genes (alpha-SMA x 2.9; TGF-beta1 x 1.6; TIMP-1 x 1.4), death receptors (CD95/Fas x 3.8; TNFR-1 x 1.4), and anti-apoptotic molecules (Bcl-2 x 2.3; Mcl-1 x 1.3). Subsequent addition of 15 microM resveratrol (LD(50) = 23.2 microM) significantly (P < 0.05) upregulated further these genes (alpha-SMA x 6.5; TGF-beta1 x 1.9; TIMP-1 x 2.2; CD95/Fas x 13.1, TNFR-1 x 2.1; Bcl-2 x 3.6; Mcl-1 x 1.9). Importantly, this effect was only observed in the presence of FFAs.

CONCLUSION

Resveratrol amplifies the profibrogenic activation of human hepatic LX-2 stellate cells. This finding raises the possibility that in obese patients with elevated FFAs reserveratrol could provoke hepatic fibrogenesis. In-vivo studies are necessary to further validate this conclusion.