Nrf2 induces interleukin-6 (IL-6) expression via an antioxidant response element within the IL-6 promoter

The effect of different concentrations of gold nanoparticles on growth performance, toxicopathological and immunological parameters of broiler chickens

The present study aimed to evaluate what dosage of gold nanoparticles (GNPs) would improve growth performance, antioxidant levels and immune defense in broiler chickens. The experiment was carried out on 90 one-day-old mixbred Cobb chicks. The birds were allocated into three groups with three replicates. Group (1) kept as a negative control. Groups (2) and (3) received 5, 15 ppm GNPs via drinking water weekly for 35 days of chicks' life. Blood samples were collected at 8, 15, 22 and 36 days for oxidative stress evaluations and immunological studies. The birds were slaughtered at the ages of 36 days and thymus, spleen, busa of Fabricius and liver were collected for histopathological description, RT-PCR analysis and DNA fragmentation assay. Our results confirmed that adding of 15ppm GNPs in drinking water were induced remarkable blood oxidative stress damage, histopathological alterations, up-regulation of IL-6, Nrf2 gene expression, and DNA fragmentation in the examined immune organs of the broiler chickens as well as a significant reduction in the antibody titer against Newcastle (ND) and avian influenza (AI) viruses were noticed. On the other hand, the group received 5 ppm GNPs noticed better growth performance with the enhancement of the final food conversion ratio (FCR) without any significant difference in the previous toxicological and immunological parameters compared with the control groups. We suggest that feeding of 5ppm GNPs could improve the antioxidant capacity, immunity and performance in poultry but further food quality assurance tests are required in the future to confirm its safety for people.

Resvega Alleviates Hydroquinone-Induced Oxidative Stress in ARPE-19 Cells

Retinal pigment epithelial (RPE) cells maintain homeostasis at the retina and they are under continuous oxidative stress. Cigarette smoke is a prominent environmental risk factor for age-related macular degeneration (AMD), which further increases the oxidant load in retinal tissues. In this study, we measured oxidative stress and inflammatory markers upon cigarette smoke-derived hydroquinone exposure on human ARPE-19 cells. In addition, we studied the effects of commercial Resvega product on hydroquinone-induced oxidative stress. Previously, it was observed that Resvega induces autophagy during impaired protein clearance in ARPE-19 cells, for which it has the potential to alleviate pro-inflammatory pathways. Cell viability was determined while using the lactate dehydrogenase (LDH) and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays, and the cytokine levels were measured using the enzyme-linked immunosorbent assay (ELISA). Reactive oxygen species (ROS) production were measured using the 2',7'-dichlorofluorescin diacetate (H₂DCFDA) probe. Hydroquinone compromised the cell viability and increased ROS production in ARPE-19 cells. Resvega significantly improved cell viability upon hydroquinone exposure and reduced the release of interleukin (IL)-8 and monocytic chemoattractant protein (MCP)-1 from RPE cells. Resvega, N-acetyl-cysteine (NAC) and aminopyrrolidine-2,4-dicarboxylic acid (APDC) alleviated hydroquinone-induced ROS production in RPE cells. Collectively, our results indicate that hydroquinone induces cytotoxicity and increases oxidative stress through NADPH oxidase activity in RPE cells, and resveratrol-containing Resvega products prevent those adverse effects.

Transcriptional activation of antioxidant gene expression by Nrf2 protects against mitochondrial dysfunction and neuronal death associated with acute and chronic neurodegeneration

Mitochondria are both a primary source of reactive oxygen species (ROS) and a sensitive target of oxidative stress; damage to mitochondria can result in bioenergetic dysfunction and both necrotic and apoptotic cell death. These relationships between mitochondria and cell death are particularly strong in both acute and chronic neurodegenerative disorders. ROS levels are affected by both the production of superoxide and its toxic metabolites and by antioxidant defense mechanisms. Mitochondrial antioxidant activities include superoxide dismutase 2, glutathione peroxidase and reductase, and intramitochondrial glutathione. When intracellular conditions disrupt the homeostatic balance between ROS production and detoxification, a net increase in ROS and an oxidized shift in cellular redox state ensues. Cells respond to this imbalance by increasing the expression of genes that code for proteins that protect against oxidative stress and inhibit cytotoxic oxidation of proteins, DNA, and lipids. If, however, the genomic response to mitochondrial oxidative stress is insufficient to maintain homeostasis, mitochondrial bioenergetic dysfunction and release of pro-apoptotic mitochondrial proteins into the cytosol initiate a variety of cell death pathways, ultimately resulting in potentially lethal damage to vital organs, including the brain. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a translational activating protein that enters the nucleus in response to oxidative stress, resulting in increased expression of numerous cytoprotective genes, including genes coding for mitochondrial and non-mitochondrial antioxidant proteins. Many experimental and some FDA-approved drugs promote this process. Since mitochondria are targets of ROS, it follows that protection against mitochondrial oxidative stress by the Nrf2 pathway of gene expression contributes to neuroprotection by these drugs. This document reviews the evidence that Nrf2 activation increases mitochondrial antioxidants, thereby protecting mitochondria from dysfunction and protecting neural cells from damage and death. New experimental results are provided demonstrating that post-ischemic administration of the Nrf2 activator sulforaphane protects against hippocampal neuronal death and neurologic injury in a clinically-relevant animal model of cardiac arrest and resuscitation.

A previously identified apoptosis inhibitor iASPP confers resistance to chemotherapeutic drugs by suppressing senescence in cancer cells

Cellular senescence is terminal cell cycle arrest that represents a prominent response to numerous anticancer therapies. The oncogene inhibitor of the apoptosis-stimulating protein of p53 (iASPP) plays essential roles in regulating cellular drug response by inhibiting apoptosis. However, whether or not it regulates chemotherapy-induced senescence (TIS) in cancer cells remains unclear. Here, using two commonly used cancer cell lines, HCT 116 and MCF-7, along with the xenograft mouse model, we found that iASPP inhibits senescence and also influences the senescence-associated secretory phenotype (SASP), which confers anticancer drug resistance independently of apoptosis. Mechanistically, iASPP is transcriptionally elevated by the p65 subunit of NF-κB in senescent cells and then translocates to the nucleus, where it binds p53 and NF-κBp65. This binding inhibits their transcriptional activities toward p21 and the key SASP factors interleukin (IL)-6/IL-8, respectively, and subsequently prevents senescence. Of note, we observed that iASPP knockdown sensitizes apoptosis-resistant cancers to doxorubicin treatment by promoting senescence both in vitro and in vivo We conclude that iASPP integrates the NF-κBp65- and p53-signaling pathways and thereby regulates cell fate in response to TIS, leading to chemotherapy resistance. These findings suggest that iASPP inhibition might be a strategy that could help restore senescence in cancer cells and improve outcomes of chemotherapy-based therapies.

Increased Circulating Levels of Interleukin-6 Affect the Redox Balance in Skeletal Muscle

The extent of oxidative stress and chronic inflammation are closely related events which coexist in a muscle environment under pathologic conditions. It has been generally accepted that the inflammatory cells, as well as myofibers, are sources of reactive species which are, in turn, able to amplify the activation of proinflammatory pathways. However, the precise mechanism underlining the physiopathologic interplay between ROS generation and inflammatory response has to be fully clarified. Thus, the identification of key molecular players in the interconnected pathogenic network between the two processes might help to design more specific therapeutic approaches for degenerative diseases. Here, we investigated whether elevated circulating levels of the proinflammatory cytokine Interleukin-6 (IL-6) are sufficient to perturb the physiologic redox balance in skeletal muscle, independently of tissue damage and inflammatory response. We observed that the overexpression of circulating IL-6 enhances the generation and accumulation of free radicals in the diaphragm muscle of adult NSE/IL-6 mice, by deregulating redox-associated molecular circuits and impinging the nuclear factor erythroid 2-related factor 2- (Nrf2-) mediated antioxidant response. Our findings are coherent with a model in which uncontrolled levels of IL-6 in the bloodstream can influence the local redox homeostasis, inducing the establishment of prooxidative conditions in skeletal muscle tissue.

Interleukin-6: Its role and mechanisms in rescuing depression-like behaviors in rat models of depression

Neuronal injury within specific brain regions is considered a critical risk factor in the pathophysiology of depression. However, the underlying mechanisms of this process, and thus the potential for development of novel therapeutic strategies in the treatment of depression, remain largely unknown. Here, we report that Il-6 protects against neuronal anomalies related with depression, in part, by suppressing oxidative stress and consequent autophagic and apoptotic hyperactivity. Specifically, we show that IL-6 is downregulated within the CA1 hippocampus in two animal models of depression and upregulated by antidepressants. Increasing levels of IL-6 in the CA1 region result in pleiotropic protective actions including reductions in oxidative stress and modulation of autophagy, anti-immuno-inflammatory activation and anti-apoptotic effects in CA1 neurons, all of which are associated with the rescue of depression-like behaviors. In contrast, IL-6 downregulation exacerbates neuronal anomalies within the CA1 region and facilitates the genesis of depression phenotypes in rats. Interestingly, in addition to attenuating oxidative damage, the antioxidant, N-acetylcysteine (NAC), is also associated with significantly decreased neuronal deficits and the display of depressive behaviors in rats. These results suggest that IL-6 may exert neuroprotection within CA1 neurons via pleiotropic mechanisms and may serve as a potential therapeutic target for the treatment of depression.

SDHA gain-of-function engages inflammatory mitochondrial retrograde signaling via KEAP1-Nrf2

Whether screening the metabolic activity of immune cells facilitates discovery of molecular pathology remains unknown. Here we prospectively screened the extracellular acidification rate as a measure of glycolysis and the oxygen consumption rate as a measure of mitochondrial respiration in B cells from patients with primary antibody deficiency. The highest oxygen consumption rate values were detected in three study participants with persistent polyclonal B cell lymphocytosis (PPBL). Exome sequencing identified germline mutations in SDHA, which encodes succinate dehydrogenase subunit A, in all three patients with PPBL. SDHA gain-of-function led to an accumulation of fumarate in PPBL B cells, which engaged the KEAP1-Nrf2 system to drive the transcription of genes encoding inflammatory cytokines. In a single patient trial, blocking the activity of the cytokine interleukin-6 in vivo prevented systemic inflammation and ameliorated clinical disease. Overall, our study has identified pathological mitochondrial retrograde signaling as a disease modifier in primary antibody deficiency.

Coumarin glycosides from Hydrangea paniculata slow down the progression of diabetic nephropathy by targeting Nrf2 anti-oxidation and smad2/3-mediated profibrosis

BACKGROUND

Water extract of Hydrangea paniculata (HP) stem, rich in coumarin glycosides, has been demonstrated to have renal protective effect in several experimental kidney injury animal models. Currently, it is under pre-clinical development as a class 5 herbal drug against membranous nephropathy. However, whether it also benefits diabetic nephropathy (DN) is not clear.

PURPOSE

This study was performed to investigate the protective effect of HP on streptozotocin-induced experimental DN, and further understand its molecular mechanisms.

METHODS

In the present study, type 1 diabetes rat model was established by the intraperitoneal injection of streptozotocin. HP was orally administered every day for three months. Biochemical analysis and histopathological staining were conducted to evaluate the renal functions. In vivo pharmacokinetic study was conducted to analyse the metabolites of HP with high blood drug concentration. In vitro assay using these metabolites was performed to analyse their ability to reduce reactive oxygen species (ROS) production induced under high glucose (HG) condition by flow cytometry. Reverse transcription-polymerase chain reaction was conducted to analyse the mRNA level of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and IL6 and western blot was performed to analyse the phosphorylation status of smad 2/3 in HK2 cells under TGFβ1 stimulation.

RESULTS

The treatment with HP significantly reduced the blood urea nitrogen and serum creatinine content, and urine albumin excretion in diabetic rats, and increased the creatinine clearance rate. Periodic acid-schiff and methenamine staining and immunohistochemistry revealed that HP also ameliorated glomerulosclerosis and tubular vacuolar degeneration, as well as the deposition of fibronectin and collagen IV in the glomeruli. Pharmacokinetic study results revealed that the major coumarin compounds from HP were metabolised into umbelliferone and esculetin. By in vitro assay, umbelliferone and esculetin were found to significantly decrease ROS production induced by HG content, as well as increase the mRNA level of Nrf2. HP and its metabolites also can down-regulate fibronectin secretion in HK2 cells stimulated by TGFβ1 and inhibit smad2/3 phosphorylation.

CONCLUSION

HP has beneficial effect on DN by increasing Nrf2 expression and inhibiting TGF-smad signal activation. Further, it can be a novel herbal drug against DN.

Effect of Mechanical Stretch on the DNCB-induced Proinflammatory Cytokine Secretion in Human Keratinocytes

Skin is exposed to various physico-chemical cues. Keratinocytes, a major component of the skin epidermis, directly interact with the surrounding extracellular matrix, and thus, biochemical and biophysical stimulations from the matrix regulate the function of keratinocytes. Although it was reported that inflammatory responses of skin were altered by an applied mechanical force, understanding how the keratinocytes sense the mechanical stimuli and regulate a cytokine secretion remains unclear. Here, we designed a device that is able to apply chemo-mechanical cues to keratinocytes and assess their proinflammatory cytokine IL-6 production. We showed that when chemical stimuli were applied with mechanical stimuli simultaneously, the IL-6 production markedly increased compared to that observed with a single stimulus. Quantitative structural analysis of cellular components revealed that the applied mechanical stretch transformed the cell morphology into an elongated shape, increased the cell size, and dictated the distribution of focal adhesion complex. Our results suggest that the mechanical cue-mediated modulation of focal adhesion proteins and actin cytoskeleton translates into intracellular signaling associated with the IL-6 production particularly in skin sensitization. Our study can be applied to understand proinflammatory responses of skin under altered biophysical environments of the skin.

Anti-Inflammatory Activity of A Polyphenolic Extract from Arabidopsis thaliana in In Vitro and In Vivo Models of Alzheimer's Disease

Alzheimer’s disease (AD) is the most common neurodegenerative disorder and the primary form of dementia in the elderly. One of the main features of AD is the increase in amyloid-beta (Aβ) peptide production and aggregation, leading to oxidative stress, neuroinflammation and neurodegeneration. Polyphenols are well known for their antioxidant, anti-inflammatory and neuroprotective effects and have been proposed as possible therapeutic agents against AD. Here, we investigated the effects of a polyphenolic extract of Arabidopsis thaliana (a plant belonging to the Brassicaceae family) on inflammatory response induced by Aβ. BV2 murine microglia cells treated with both Aβ_25–35 peptide and extract showed a lower pro-inflammatory (IL-6, IL-1β, TNF-α) and a higher anti-inflammatory (IL-4, IL-10, IL-13) cytokine production compared to cells treated with Aβ only. The activation of the Nrf2-antioxidant response element signaling pathway in treated cells resulted in the upregulation of heme oxygenase-1 mRNA and in an increase of NAD(P)H:quinone oxidoreductase 1 activity. To establish whether the extract is also effective against Aβ-induced neurotoxicity in vivo, we evaluated its effect on the impaired climbing ability of AD Drosophila flies expressing human Aβ_1–42. Arabidopsis extract significantly restored the locomotor activity of these flies, thus confirming its neuroprotective effects also in vivo. These results point to a protective effect of the Arabidopsis extract in AD, and prompt its use as a model in studying the impact of complex mixtures derived from plant-based food on neurodegenerative diseases.

Nrf2 deficiency aggravates Angiotensin II-induced cardiac injury by increasing hypertrophy and enhancing IL-6/STAT3-dependent inflammation

BACKGROUND

NF-E2-related factor 2 (Nrf2) is a transcription factor playing cytoprotective effects in various pathological processes including oxidative stress and cardiac hypertrophy. Despite being a potential therapeutic target to treat several cardiomyopathies, the signaling underlying Nrf2-dependent cardioprotective action remains largely uncharacterized.

AIM

This study aimed to explore the signaling mediating the role of Nrf2 in the development of hypertensive cardiac pathogenesis by analyzing the response to Angiotensin II (Ang II) in the presence or absence of Nrf2 expression, both in vivo and in vitro.

RESULTS

Our results indicated that Nrf2 deficiency exacerbated cardiac damage triggered by Ang II infusion. Mechanistically, our study shows that Ang II-triggered hypertrophy and inflammation is exacerbated in the absence of Nrf2 expression and points to the involvement of the IL-6/STAT3 signaling pathway in this event. Indeed, our results show that IL-6 abundance triggered by Ang II is increased in the absence of Nrf2 and demonstrate the requirement of IL-6 in STAT3 activation and cardiac inflammation induced by Ang II.

CONCLUSION

Our results show that Nrf2 is important for the protection of the heart against Ang II-induced cardiac hypertrophy and inflammation by mechanisms involving the regulation of IL-6/STAT3-dependent signaling.

Mitochondrial Impairment in Oligodendroglial Cells Induces Cytokine Expression and Signaling

Widespread inflammatory lesions within the central nervous system grey and white matter are major hallmarks of multiple sclerosis. The development of full-blown demyelinating multiple sclerosis lesions might be preceded by preactive lesions which are characterized by focal microglia activation in close spatial relation to apoptotic oligodendrocytes. In this study, we investigated the expression of signaling molecules of oligodendrocytes that might be involved in initial microglia activation during preactive lesion formation. Sodium azide was used to trigger mitochondrial impairment and cellular stress in oligodendroglial cells in vitro. Among various chemokines and cytokines, IL6 was identified as a possible oligodendroglial cell-derived signaling molecule in response to cellular stress. Relevance of this finding for lesion development was further explored in the cuprizone model by applying short-term cuprizone feeding (2-4 days) on male C57BL/6 mice and subsequent analysis of gene expression, in situ hybridization and histology. Additionally, we analyzed the possible signaling of stressed oligodendroglial cells in vitro as well as in the cuprizone mouse model. In vitro, conditioned medium of stressed oligodendroglial cells triggered the activation of microglia cells. In cuprizone-fed animals, IL6 expression in oligodendrocytes was found in close vicinity of activated microglia cells. Taken together, our data support the view that stressed oligodendrocytes have the potential to activate microglia cells through a specific cocktail of chemokines and cytokines among IL6. Further studies will have to identify the temporal activation pattern of these signaling molecules, their cellular sources, and impact on neuroinflammation.

Embryotropic effects of vascular endothelial growth factor on porcine embryos produced by in vitro fertilization

Current research suggests that supplementing in vitro culture (IVC) media with vascular endothelial growth factor (VEGF) may have beneficial effects on the development of porcine embryos in vitro. However, the molecular signaling mechanisms underlying this effect are unclear. Therefore, we aimed to investigate the effects of VEGF on molecular signaling events during in vitro embryonic development of porcine embryos. Porcine oocytes matured in vitro were fertilized, and the resultant zygotes were cultured with 5 ng/mL of VEGF supplemented with or without fetal bovine serum from day 4 till day 7. Without VEGF and/or FBS served as the control group. Real-time quantitative PCR was used to detect expression patterns of apoptosis- and oxidative stress-related genes in day 7 blastocysts (BLs). Early-stage apoptosis was detected by annexin-V assays in day 2 and day 7 embryos. We found that the addition of VEGF throughout the culture period with or without FBS supplementation significantly improved embryo survival and development. Supplementation with VEGF in the IVC medium significantly increased early BL formation (p < 0.05), although addition of FBS on day 4 significantly increased hatched BL formation (p < 0.05) regardless of VEGF supplementation. However, supplementation of media with both VEGF and FBS increased the formation of expanded BLs synergistically. The average total cell numbers per BL were significantly (p < 0.05) higher in embryos supplemented with VEGF and FBS than in those supplemented with either VEGF or FBS alone. We also found that accumulation of reactive oxygen species in VEGF-treated embryos was significantly lower (p < 0.05) than that in untreated embryos. The mRNA levels of caspase-3 were significantly lower (p < 0.05), and those of Bcl-2 and Nrf-2 were significantly higher (p < 0.05) in embryos grown in VEGF-supplemented media than in embryos grown in non-supplemented media. Furthermore, on day 2, the numbers of viable embryos (44.06 ± 3.94%) and blastomeres (67.18 ± 3.60%) were significantly higher (p < 0.05), and the numbers of early apoptotic embryos (55.94 ± 3.94) and blastomeres (23.23 ± 4.22) were significantly lower (p < 0.05) in VEGF-treated BLs than in controls. Furthermore, the numbers of early apoptotic cells in BLs on day 7 were also significantly lower (p < 0.05) in VEGF-treated BLs than in controls. Overall, our results indicate that supplementing IVC media with VEGF during in vitro culture of porcine embryos increases their developmental potential.

Interleukin-6 Reduces β-Cell Oxidative Stress by Linking Autophagy With the Antioxidant Response

Production of reactive oxygen species (ROS) is a key instigator of β-cell dysfunction in diabetes. The pleiotropic cytokine interleukin 6 (IL-6) has previously been linked to β-cell autophagy but has not been studied in the context of β-cell antioxidant response. We used a combination of animal models of diabetes and analysis of cultured human islets and rodent β-cells to study how IL-6 influences antioxidant response. We show that IL-6 couples autophagy to antioxidant response and thereby reduces ROS in β-cells and human islets. β-Cell-specific loss of IL-6 signaling in vivo renders mice more susceptible to oxidative damage and cell death through the selective β-cell toxins streptozotocin and alloxan. IL-6-driven ROS reduction is associated with an increase in the master antioxidant factor NRF2, which rapidly translocates to the mitochondria to decrease mitochondrial activity and stimulate mitophagy. IL-6 also initiates a robust transient decrease in cellular cAMP levels, likely contributing to the stimulation of mitophagy to mitigate ROS. Our findings suggest that coupling autophagy to antioxidant response in β-cells leads to stress adaptation that can reduce cellular apoptosis. These findings have implications for β-cell survival under diabetogenic conditions and present novel targets for therapeutic intervention.

Bevacizumab Diminishes Inflammation in an Acute Endotoxin-Induced Uveitis Model

Introduction: Uveitis is an eye disease characterized by inflammation of the uvea and an early and exhaustive diagnosis is essential for its treatment. The aim of our study is to assess the potential toxicity and anti-inflammatory efficacy of Bevacizumab in an experimental uveitis model by subcutaneously injecting lipopolysaccharide into Lewis rats and to clarify its mechanism. Material and Methods: Blood-aqueous barrier integrity was assessed 24 h after endotoxin-induced uveitis (EIU) by analyzing two parameters: cell count and protein concentration in aqueous humors. Histopathology of all eye structures was also studied. Enzyme-linked immunosorbent analyses of the aqueous humor samples were performed in order to calculate the diverse chemokine and cytokine protein levels and oxidative stress-related markers were also evaluated. Results: The aqueous humor's cellular content significantly increased in the group treated with only Bevacizumab, but it had no effect on retina histopathological grading. Nevertheless, the inflammation noted in ocular structures when administering Bevacizumab with endotoxin was mostly prevented since aqueous humor cell content considerably lowered, and concomitantly with a sharp drop in uveal, vitreous, and retina histopathological grading. The values of the multi-faceted cytokine IL-2 also significantly decreased (p < 0.05 vs. endotoxin group), and the protective IL-6 and IL-10 cytokines values rose with related anti-oxidant system recovery (p < 0.05 vs. endotoxin group). Concurrently, some related M1 macrophage chemokines substantially increased, e.g., GRO/KC, a chemokine that also displays any kind of protective role. Conclusion: All these results revealed that 24 h after being administered, Bevacizumab treatment in EIU significantly prevented inflammation in various eye structures and correct results in efficacy vs. toxicity balance were obtained.

Soluble factors from stellate cells induce pancreatic cancer cell proliferation via Nrf2-activated metabolic reprogramming and ROS detoxification

Pancreatic stellate cells (PSC), a prominent stromal cell, contribute to the progression of pancreatic ductal adenocarcinoma (PDAC). We aim to investigate the mechanisms by which PSC promote cell proliferation in PDAC cell lines, BxPC-3 and AsPC-1. PSC-conditioned media (PSC-CM) induced proliferation of these cells in a dose- and time-dependent manner. Nrf2 protein was upregulated and subsequently, its transcriptional activity was increased with greater DNA binding activity and transcription of target genes. Downregulation of Nrf2 led to suppression of PSC-CM activity in BxPC-3, but not in AsPC-1 cells. However, overexpression of Nrf2 alone resulted in increased cell proliferation in both cell lines, and treatment with PSC-CM further enhanced this effect. Activation of Nrf2 pathway resulted in upregulation of metabolic genes involved in pentose phosphate pathway, glutaminolysis and glutathione biosynthesis. Downregulation and inhibition of glucose-6-phosphate-dehydrogenase with siRNA and chemical approaches reduced PSC-mediated cell proliferation. Among the cytokines present in PSC-CM, stromal-derived factor-1 alpha (SDF-1α) and interleukin-6 (IL-6) activated Nrf2 pathway to induce cell proliferation in both cells, as shown with neutralization antibodies, recombinant proteins and signaling inhibitors. Taken together, SDF-1α and IL-6 secreted from PSC induced PDAC cell proliferation via Nrf2-activated metabolic reprogramming and ROS detoxification.

The complex roles of STAT3 and STAT5 in maintaining redox balance: Lessons from STAT-mediated xCT expression in cancer cells

STAT3 and STAT5 mediate diverse cellular processes, transcriptionally regulating gene expression and interacting with cytoplasmic proteins. Their canonical activity is stimulated by cytokines/growth factors through JAK-STAT signaling. As targets of oncogenes with intrinsic tyrosine kinase activity, STAT3 and STAT5 become constitutively active in hematologic neoplasms and solid tumors, promoting cell proliferation and survival and modulating redox homeostasis. This review summarizes reactive oxygen species (ROS)-regulated STAT activation and how STATs influence ROS production. ROS-induced effects on post-translational modifications are presented, and STAT3/5-mediated regulation of xCT, a redox-sensitive target up-regulated in numerous cancers, is discussed with regard to transcriptional cross-talk.

Dietary vitamin B6 modulates the gene expression of myokines, Nrf2-related factors, myogenin and HSP60 in the skeletal muscle of rats

Previous studies have suggested that vitamin B6 is an ergogenic factor. However, the role of dietary vitamin B6 in skeletal muscle has not been widely researched. The aim of the present study was to investigate the effects of dietary vitamin B6 on the gene expression of 19 myokines, 14 nuclear factor erythroid 2-related factor 2 (Nrf2)-regulated factors, 8 myogenesis-related factors and 4 heat shock proteins (HSPs), which may serve important roles in skeletal muscles. Rats were fed a diet containing 1 (marginal vitamin B6 deficiency), 7 (recommended dietary level) or 35 mg/kg of pyridoxine (PN) HCl/ for 6 weeks. Gene expressions were subsequently analysed using reverse transcription-quantitative polymerase chain reaction. Food intake and growth were unaffected by this dietary treatment. The rats in the 7 and 35 mg/kg PN HCl groups exhibited a significant increase in the concentration of pyridoxal 5'-phosphate in the gastrocnemius muscle compared with the 1 mg/kg PN HCl diet (P<0.01). The expressions of myokines, such as IL-7, IL-8, secreted protein acidic and rich in cysteine, IL-6, growth differentiation factor 11, myonectin, leukaemia inhibitory factor, apelin and retinoic acid receptor responder (tazarotene induced) 1, the expression of Nrf2 and its regulated factors, such as heme oxygenase 1, superoxide dismutase 2, glutathione peroxidase 1 and glutathione S-transferase, and the expression of myogenin and HSP60 were significantly elevated in the 7 mg/kg PN HCl group compared with the 1 mg/kg PN HCl diet (P<0.05). No significant differences in levels of these genes were observed between the 35 and 1 mg/kg PN HCl, with the exception of GDF11 and myonectin, whose expressions were significantly increased in the 35 mg/kg PN HCl (P<0.05). Notably, the majority of gene expressions that were affected responded to dietary supplemental vitamin B6 in a similar manner. The results suggest that compared with the marginal vitamin B6 deficiency, the recommended dietary intake of vitamin B6 upregulates the gene expression of a number of factors that promote the growth and repair of skeletal muscle.

Intersection of retinoblastoma tumor suppressor function, stem cells, metabolism, and inflammation

The Retinoblastoma (RB) tumor suppressor regulates G₁/S transition during cell cycle progression by modulating the activity of E2F transcription factors. The RB pathway plays a central role in the suppression of most cancers, and RB mutation was initially discovered by virtue of its role in tumor initiation. However, as cancer genome sequencing has evolved to profile more advanced and treatment‐resistant cancers, it has become increasingly clear that, in the majority of cancers, somatic RB inactivation occurs during tumor progression. Furthermore, despite the presence of deregulation of cell cycle control due to an INK4A deletion, additional CCND amplification and/or other mutations in the RB pathway, mutation or deletion of the RB gene is often observed during cancer progression. Of note, RB inactivation during cancer progression not only facilitates G₁/S transition but also enhances some characteristics of malignancy, including altered drug sensitivity and a return to the undifferentiated state. Recently, we reported that RB inactivation enhances pro‐inflammatory signaling through stimulation of the interleukin‐6/STAT3 pathway, which directly promotes various malignant features of cancer cells. In this review, we highlight the consequences of RB inactivation during cancer progression, and discuss the biological and pathological significance of the interaction between RB and pro‐inflammatory signaling.

Fumarate decreases edema volume and improves functional outcome after experimental stroke

BACKGROUND

Oxidative stress and inflammation exacerbate tissue damage in the brain after ischemic stroke. Dimethyl-fumarate (DMF) and its metabolite monomethyl-fumarate (MMF) are known to stimulate anti-oxidant pathways and modulate inflammatory responses. Considering these dual effects of fumarates, we examined the effect of MMF treatment after ischemic stroke in mice.

METHODS

Permanent middle cerebral artery occlusion (pMCAO) was performed using adult, male C57BL/6 mice. Thirty minutes after pMCAO, 20mg/kg MMF was administered intravenously. Outcomes were evaluated 6, 24 and 48h after pMCAO. First, we examined whether a bolus of MMF was capable of changing expression of kelch-like erythroid cell-derived protein with CNC homology-associated protein 1 (Keap1) and nuclear factor erythroid 2-related factor (Nrf)2 in the infarcted brain. Next, we studied the effect of MMF on functional recovery. To explore mechanisms potentially influencing functional changes, we examined infarct volumes, edema formation, the expression of heat shock protein (Hsp)72, hydroxycarboxylic acid receptor 2 (Hcar2), and inducible nitric oxide synthase (iNOS) in the infarcted brain using real-time PCR and Western blotting. Concentrations of a panel of pro- and anti-inflammatory cytokines (IFNγ, IL-1β, IL-2, IL-4, IL-5, IL-6, IL-10, IL-12p70, TNF) were examined in both the infarcted brain tissue and plasma samples 6, 24 and 48h after pMCAO using multiplex electrochemoluminiscence analysis.

RESULTS

Administration of MMF increased the protein level of Nrf2 6h after pMCAO, and improved functional outcome at 24 and 48h after pMCAO. MMF treatment did not influence infarct size, however reduced edema volume at both 24 and 48h after pMCAO. MMF treatment resulted in increased Hsp72 expression in the brain 6h after pMCAO. Hcar2 mRNA levels increased significantly 24h after pMCAO, but were not different between saline- and MMF-treated mice. MMF treatment also increased the level of the anti-inflammatory cytokine IL-10 in the brain and plasma 6h after pMCAO, and additionally reduced the level of the pro-inflammatory cytokine IL-12p70 in the brain at 24 and 48h after pMCAO.

CONCLUSIONS

A single intravenous bolus of MMF improved sensory-motor function after ischemic stroke, reduced edema formation, and increased the levels of the neuroprotective protein Hsp72 in the brain. The early increase in IL-10 and reduction in IL-12p70 in the brain combined with changes in systemic cytokine levels may also contribute to the functional recovery after pMCAO.

Psoriasin has divergent effects on the innate immune responses of murine glial cells

Antimicrobial peptides are an important part of the innate immune defense in the central nervous system (CNS). The expression of the antimicrobial peptides psoriasin (S100A7) is up-regulated during bacterial meningitis. However, the exact mechanisms induced by psoriasin to modulate glial cell activity are not yet fully understood. Our hypothesis is that psoriasin induced pro- and anti-inflammatory signaling pathways as well as regenerative factors to contribute in total to a balanced immune response. Therefore, we used psoriasin-stimulated glial cells and analyzed the translocation of the pro-inflammatory transcription factor nuclear factor 'kappa-light-chain-enhancer' of activated B-cells (NFκB) in murine glial cells and the expression of pro- and anti-inflammatory mediators by real time RT-PCR, ELISA technique, and western blotting. Furthermore, the relationship between psoriasin and the antioxidative stress transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) was investigated. Stimulation with psoriasin not only enhanced NFκB translocation and increased the expression of the pro-inflammatory cytokines, interleukin-6 (IL-6) and tumor necrosis factor-α (TNF- α) but also neurotrophin expression. Evidence for functional interactions between psoriasin and Nrf2 were detected in the form of increased antioxidant response element (ARE) activity and induction of Nrf2/ARE-dependent heme oxygenase 1 (HO-1) expression in psoriasin-treated microglia and astrocytes. The results illustrate the ability of psoriasin to induce immunological functions in glia cells where psoriasin exerts divergent effects on the innate immune response.

Nrf2 signaling pathway: Pivotal roles in inflammation

Inflammation is the most common feature of many chronic diseases and complications, while playing critical roles in carcinogenesis. Several studies have demonstrated that Nrf2 contributes to the anti-inflammatory process by orchestrating the recruitment of inflammatory cells and regulating gene expression through the antioxidant response element (ARE). The Keap1 (Kelch-like ECH-associated protein)/Nrf2 (NF-E2 p45-related factor 2)/ARE signaling pathway mainly regulates anti-inflammatory gene expression and inhibits the progression of inflammation. Therefore, the identification of new Nrf2-dependent anti-inflammatory phytochemicals has become a key point in drug discovery. In this review, we discuss the members of the Keap1/Nrf2/ARE signal pathway and its downstream genes, the effects of this pathway on animal models of inflammatory diseases, and crosstalk with the NF-κB pathway. In addition we also discuss about the regulation of NLRP3 inflammasome by Nrf2. Besides this, we summarize the current scenario of the development of anti-inflammatory phytochemicals and others that mediate the Nrf2/ARE signaling pathway.

Influence of sex and developmental stage on acute hepatotoxic and inflammatory responses to liver procarcinogens in the mouse

The incidence of liver cancer is higher in men than in women. This sex difference is also observed in murine tumor induction models that result in the appearance of liver tumors in adult mice following their exposure on postnatal days 8 and/or 15 to carcinogens such as 4-aminobiphenyl (ABP) or diethylnitrosamine (DEN). Previous studies performed in adult mice showed that acute hepatotoxic and inflammatory responses to high-dose DEN exposure were greater in males than in females, leading to the suggestion that these responses could account for the sex difference in tumor development. We also recently observed that female but not male mice exposed postnatally to ABP had slightly increased expression of the antioxidant defense genes Nqo1 and Ggt1, which are regulated by the oxidative stress response protein nuclear factor erythroid 2-related factor 2 (NRF2), while expression of Hmox1 was increased in both sexes. The goal of the present study was therefore to compare selected acute hepatotoxic, inflammatory and oxidative stress defense responses to ABP, DEN, or the prototype hepatotoxicant carbon tetrachloride (CCl₄), in male and female mice exposed to these chemicals either postnatally or as adults. Exposure of adult mice to ABP, DEN or CCl₄ produced a 2-fold greater acute elevation in serum levels of the hepatotoxicity biomarker alanine aminotransferase (ALT) in males than in females, while levels of the inflammatory biomarker interleukin-6 (IL-6) showed no sex difference. However, treatment of immature mice with either ABP or DEN using standard tumor-inducing postnatal exposure protocols produced no increase in serum ALT or IL-6 levels in either males or females, while CCl₄ produced a 40-fold ALT elevation but with no sex difference. Basal expression of the NRF2-responsive gene Nqo1 was higher in adult females than in males, but there was no sex difference in basal expression of Ggt1 or Hmox1. Sexually immature animals showed no sex difference in basal expression of any of the three genes. Postnatal DEN exposure modestly increased the expression of Ggt1 only in male mice and Nqo1 in both sexes, while CCl₄ slightly increased expression of Ggt1 in both males and females and Nqo1 only in females. Taken together, our results make it unlikely that acute hepatotoxic, inflammatory or NRF2-activated gene responses account for the male predominance in liver tumor growth following postnatal carcinogen exposure in mice. Our findings also suggest that acute toxicity studies performed in adult mice should be interpreted with caution when extrapolating potential mechanisms to liver carcinogenesis models that commonly use postnatally exposed mice.

Sulforaphane protects against rotenone-induced neurotoxicity in vivo: Involvement of the mTOR, Nrf2, and autophagy pathways

Sulforaphane, a naturally occurring compound found in cruciferous vegetables, has been shown to be neuroprotective in several neurological disorders. In this study, we sought to investigate the potential protective effects and associated molecular mechanisms of sulforaphane in an in vivo Parkinson's disease (PD) model, based on rotenone-mediated neurotoxicity. Our results showed that sulforaphane inhibited rotenone-induced locomotor activity deficiency and dopaminergic neuronal loss. Additionally, sulforaphane treatment inhibited the rotenone-induced reactive oxygen species production, malondialdehyde (MDA) accumulation, and resulted in an increased level of total glutathione and reduced glutathione (GSH): oxidized glutathione (GSSG) in the brain. Western blot analysis illustrated that sulforaphane increased the expression of nuclear factor (erythroid-derived 2)-like 2 (Nrf2), heme oxygenase-1 (HO-1), and NAD(P)H quinone oxidoreductase (NQO1), the latter two of which are anti-oxidative enzymes. Moreover, sulforaphane treatment significantly attenuated rotenone-inhibited mTOR-mediated p70S6K and 4E-BP1 signalling pathway, as well as neuronal apoptosis. In addition, sulforaphane rescued rotenone-inhibited autophagy, as detected by LC3-II. Collectively, these findings demonstrated that sulforaphane exert neuroprotective effect involving Nrf2-dependent reductions in oxidative stress, mTOR-dependent inhibition of neuronal apoptosis, and the restoration of normal autophagy. Sulforaphane appears to be a promising compound with neuroprotective properties that may play an important role in preventing PD.

Nrf2 suppresses macrophage inflammatory response by blocking proinflammatory cytokine transcription

Nrf2 (NF-E2-related factor-2) transcription factor regulates oxidative/xenobiotic stress response and also represses inflammation. However, the mechanisms how Nrf2 alleviates inflammation are still unclear. Here, we demonstrate that Nrf2 interferes with lipopolysaccharide-induced transcriptional upregulation of proinflammatory cytokines, including IL-6 and IL-1β. Chromatin immunoprecipitation (ChIP)-seq and ChIP-qPCR analyses revealed that Nrf2 binds to the proximity of these genes in macrophages and inhibits RNA Pol II recruitment. Further, we found that Nrf2-mediated inhibition is independent of the Nrf2-binding motif and reactive oxygen species level. Murine inflammatory models further demonstrated that Nrf2 interferes with IL6 induction and inflammatory phenotypes in vivo. Thus, contrary to the widely accepted view that Nrf2 suppresses inflammation through redox control, we demonstrate here that Nrf2 opposes transcriptional upregulation of proinflammatory cytokine genes. This study identifies Nrf2 as the upstream regulator of cytokine production and establishes a molecular basis for an Nrf2-mediated anti-inflammation approach.

Nrf2 is a transcriptional activator of oxidative stress response genes. Here the authors show that Nrf2 binds to promoters of proinflammatory genes and interferes with their transcriptional upregulation in LPS-stimulated macrophages independently of its role in regulation of reactive oxygen species.

Hyperammonemia induces glial activation, neuroinflammation and alters neurotransmitter receptors in hippocampus, impairing spatial learning: reversal by sulforaphane

Background

Patients with liver cirrhosis and minimal hepatic encephalopathy (MHE) show mild cognitive impairment and spatial learning dysfunction. Hyperammonemia acts synergistically with inflammation to induce cognitive impairment in MHE. Hyperammonemia-induced neuroinflammation in hippocampus could contribute to spatial learning impairment in MHE. Two main aims of this work were: (1) to assess whether chronic hyperammonemia increases inflammatory factors in the hippocampus and if this is associated with microglia and/or astrocytes activation and (2) to assess whether hyperammonemia-induced neuroinflammation in the hippocampus is associated with altered membrane expression of glutamate and GABA receptors and spatial learning impairment. There are no specific treatments for cognitive alterations in patients with MHE. A third aim was to assess whether treatment with sulforaphane enhances endogenous the anti-inflammatory system, reduces neuroinflammation in the hippocampus of hyperammonemic rats, and restores spatial learning and if normalization of receptor membrane expression is associated with learning improvement.

Methods

We analyzed the following in control and hyperammonemic rats, treated or not with sulforaphane: (1) microglia and astrocytes activation by immunohistochemistry, (2) markers of pro-inflammatory (M1) (IL-1β, IL-6) and anti-inflammatory (M2) microglia (Arg1, YM-1) by Western blot, (3) membrane expression of GABA, AMPA, and NMDA receptors using the BS3 cross-linker, and (4) spatial learning using the radial maze.

Results

The results reported show that hyperammonemia induces astrocytes and microglia activation in the hippocampus, increasing pro-inflammatory cytokines IL-1β and IL-6. This is associated with altered membrane expression of AMPA, NMDA, and GABA receptors which would be responsible for altered neurotransmission and impairment of spatial learning in the radial maze. Treatment with sulforaphane promotes microglia differentiation from pro-inflammatory M1 to anti-inflammatory M2 phenotype and reduces activation of astrocytes in hyperammonemic rats. This reduces neuroinflammation, normalizes membrane expression of glutamate and GABA receptors, and restores spatial learning in hyperammonemic rats.

Conclusions

Hyperammonemia-induced neuroinflammation impairs glutamatergic and GABAergic neurotransmission by altering membrane expression of glutamate and GABA receptors, resulting in impaired spatial learning. Sulforaphane reverses all these effects. Treatment with sulforaphane could be useful to improve cognitive function in cirrhotic patients with minimal or clinical hepatic encephalopathy.

HBV-induced ROS accumulation promotes hepatocarcinogenesis through Snail-mediated epigenetic silencing of SOCS3

Interleukin-6 (IL-6) has been demonstrated to be involved in Hepatitis B virus (HBV)-associated hepatocarcinogenesis through activation of the STAT3 pathway. The sustained activation of the IL-6/STAT3 pathway is frequently associated with repression of SOCS3, which is both a target gene and a negative regulator of STAT3. However, the silencing mechanism of SOCS3 in hepatocellular carcinoma (HCC) remains to be elucidated. Here, we showed that the repression of SOCS3 and sustained activation of IL-6/STAT3 pathway in HBV-producing HCC cells were caused by HBV-induced mitochondrial ROS accumulation. Mechanistic studies revealed that ROS-mediated DNA methylation resulted in the silencing of SOCS3. Decreased SOCS3 expression significantly promoted the proliferation of HCC cells and growth of tumor xenografts in mice. Further studies revealed that HBV-induced ROS accumulation upregulated the expression of the transcription factor, Snail, which bound to the E-boxes of SOCS3 promoter and mediated the epigenetic silencing of SOCS3 in association with DNMT1 and HDAC1. In addition, we found that the expression of Snail and SOCS3 were inversely correlated in HBV-associated HCC patients, suggesting that SOCS3 and/or Snail could be used as prognostic markers in HCC pathogenesis. Taken together, our data show that HBV-induced mitochondrial ROS production represses SOCS3 expression through Snail-mediated epigenetic silencing, leading to the sustained activation of IL-6/STAT3 pathway and ultimately contributing to hepatocarcinogenesis.

Nrf2 in health and disease: current and future clinical implications

The transcription factor Nrf2 (nuclear factor erythroid 2-related factor 2) is a major regulator of oxidative stress defence in the human body. As Nrf2 regulates the expression of a large battery of cytoprotective genes, it plays a crucial role in the prevention of degenerative disease in multiple organs. Thus it has been the focus of research as a pharmacological target that could be used for prevention and treatment of chronic diseases such as multiple sclerosis, chronic kidney disease or cardiovascular diseases. The present review summarizes promising findings from basic research and shows which Nrf2-targeting therapies are currently being investigated in clinical trials and which agents have already entered clinical practice.

Crosstalk between Nrf2 and Notch signaling

The transcription factor Nrf2 (nuclear factor, erythroid derived 2, like 2) belongs to the CNC-bZip protein family, forming a transcriptosome with its direct heterodimer partner, sMaf, and co-factors such as CBP/p300. Nrf2 binds to one or more AREs (antioxidant response elements) that are located in the gene regulatory regions of the hundreds of Nrf2 target genes. The AREs are key enhancers that are activated in response to endogenous or exogenous stresses to maintain cellular and tissue homeostasis. Data emanating from gene expression microarray analyses comparing Nrf2-disrupted and wild-type mouse embryonic fibroblasts (MEF) showed that expression of Notch1 and Notch-signaling-related genes were decreased in Nrf2-disrupted cells. This observation triggered our research on Nrf2-Notch crosstalk. A functional ARE has been identified upstream of the Notch1 major transcription start site. Furthermore, an Rbpjκ binding site is conserved on the promoters of Nrf2 among animal species. Notch1 is one of the transmembrane Notch family receptors that drive Notch signaling, together with the Rbpjκ transcription factor. After canonically accepting ligands such as Jags and Deltas, the receptor undergoes cleavage to yield the Notch intracellular domain, which translocates to the nucleus. Recent studies using conditional knockout mice indicate that Notch1 as well as Notch2 plays an important role postnatally in liver development and in maintenance of hepatic function. In this review, we summarize current understanding of the role of reciprocal transcriptional regulation between Nrf2 and Notch in adult liver from studies using Nrf2, Keap1, and Notch1 genetically engineered mice.

Activation of NRF2 pathway in spleen, thymus as well as peripheral blood mononuclear cells by acute arsenic exposure in mice

Arsenic has already been demonstrated to activate the nuclear factor erythroid 2-related factor 2 (NRF2) in many different organs and cell lines. The present study tried to explore the expression of NRF2 pathway by acute arsenic exposure in immune system in vivo. Our results showed that treatment with arsenic (sodium arsenite, 5, 10 and 20mg/kg, intra-gastrically) increased the expression of NRF2 and its downstream targets heme oxygenase-1 (HO-1), glutathione-S-transferase (GST), glutamate-cysteine ligase (GCL) and glutathione reductase (GR) consistently in spleen, thymus, as well as peripheral blood mononuclear cells (PBMCs), as early as treatment from 6h. Arsenic was also detected to up-regulate the mRNA levels of Hmox1, NAD(P)H: quinine oxidoreductase 1 (Nqo1), Gclc and Gclm in spleen and thymus. Besides, we detected the enhancement of Kelch-like ECH-associated protein (KEAP1) expression in these immune organs and immunocytes. What's more, our results also found the imbalanced oxidative redox status under the circumstances that arsenic activated NRF2 pathway, reflected by the generation of lipid peroxidation, as well as the reduction of antioxidative capacities in both spleen and thymus. Taken together, our results here strongly suggested the expression and activation of NRF2 pathway by acute arsenic exposure in immune system in vivo. Further studies are being investigated to explore the possible roles and functions of NRF2 pathway stimulation in the regulation of immune responses of this metalloid.

Keap1-Nrf2 Interaction Suppresses Cell Motility in Lung Adenocarcinomas by Targeting the S100P Protein

PURPOSE

Kelch-like ECH-associated protein 1 (Keap1) is an E3 ligase participated in the cellular defense response against oxidative stress through nuclear factor erythroid-2-related factor 2 (Nrf2). However, the role of Keap1 in regulating cancer motility is still controversial. We investigated the contribution of the Keap1-Nrf2 axis in the progression of non-small cell lung cancer (NSCLC).

EXPERIMENTAL DESIGN

The expression of Keap1 and Nrf2 was examined via immunohistochemistry, real-time PCR, and Western blot analysis in a cohort of NSCLC tissues and cells. A series of in vivo and in vitro assays was performed to elucidate the contribution of the Keap1-Nrf2 axis in lung cancer mobility and progression.

RESULTS

Keap1 expression was decreased in specimens from NSCLC patients with lymph node metastasis compared with patients without metastasis. Higher Keap1 expression levels were correlated with the survival of NSCLC patients. Moreover, manipulation of Keap1 expression affected cell migration/invasion abilities. Depletion of Nrf2 relieved the migration promotion imposed by Keap1 suppression. Mechanistic investigations found that S100P was downregulated in both Keap1-overexpressing and Nrf2-knockdown NSCLC cells. Overexpression of Keap1 and knockdown of Nrf2 both suppressed S100P expression in NSCLC cells. Knockdown of S100P inhibited cell migration in highly invasive NSCLC cells and also relieved the migration promotion imposed by Keap1 suppression in weakly invasive NSCLC cells.

CONCLUSIONS

Our findings suggest that Keap1 functions as a suppressor of tumor metastasis by targeting the Nrf2/S100P pathway in NSCLC cells. In addition, overexpression of Keap1 may be a novel NSCLC treatment strategy and/or useful biomarker for predicting NSCLC progression.

Polyphenol Stilbenes: Molecular Mechanisms of Defence against Oxidative Stress and Aging-Related Diseases

Numerous studies have highlighted the key roles of oxidative stress and inflammation in aging-related diseases such as obesity, type 2 diabetes, age-related macular degeneration (AMD), and Alzheimer's disease (AD). In aging cells, the natural antioxidant capacity decreases and the overall efficiency of reparative systems against cell damage becomes impaired. There is convincing data that stilbene compounds, a diverse group of natural defence phenolics, abundant in grapes, berries, and conifer bark waste, may confer a protective effect against aging-related diseases. This review highlights recent data helping to clarify the molecular mechanisms involved in the stilbene-mediated protection against oxidative stress. The impact of stilbenes on the nuclear factor-erythroid-2-related factor-2 (Nrf2) mediated cellular defence against oxidative stress as well as the potential roles of SQSTM1/p62 protein in Nrf2/Keap1 signaling and autophagy will be summarized. The therapeutic potential of stilbene compounds against the most common aging-related diseases is discussed.

Clinical associations of host genetic variations in the genes of cytokines in critically ill patients

Host genetic variations may influence a changing profile of biochemical markers and outcome in patients with trauma/injury. The objective of this study was to assess clinical associations of single nucleotide polymorphisms (SNPs) in the genes of cytokines in critically ill patients. A total of 430 patients were genotyped for SNPs in the genes of pro- (IL1B, IL6, IL8) and anti-inflammatory (IL4, IL10, IL13) cytokines. The main end-points were sepsis, mortality and adult respiratory distress syndrome (ARDS). We evaluated the dynamic levels of bilirubin, blood urea nitrogen, creatine kinase, creatinine and lactate dehydrogenase in five points of measurements (between 1 and 14 days after admission) and correlated them with SNPs. High-producing alleles of proinflammatory cytokines protected patients against sepsis (IL1B -511A and IL8 -251A) and mortality (IL1B -511A). High-producing alleles of anti-inflammatory cytokines IL4 -589T and IL13 431A (144Gln) were less frequent in ARDS patients. The carriers of IL6 -174C/C genotypes were prone to the increased levels of biochemical markers and acute kidney and liver insufficiency. Genotype-dependent differences in the levels of biochemical indicators gradually increased to a maximal value on the 14th day after admission. These findings suggest that genetic variability in pro- and anti-inflammatory cytokines may contribute to different clinical phenotypes in patients at high risk of critical illness.

Organic extracts from African dust storms stimulate oxidative stress and induce inflammatory responses in human lung cells through Nrf2 but not NF-κB

The health impact of the global African dust event (ADE) phenomenon in the Caribbean has been vaguely investigated. Heavy metals in ADE and non-ADE extracts were evaluated for the formation of reactive oxygen species (ROS) and antioxidant capacity by cells using, deferoxamine mesylate (DF) and N-acetyl-l-cysteine (NAC). Results show that ADE particulate matter 2.5 (PM2.5) induces ROS and stimulates oxidative stress. Pre-treatment with DF reduces ROS in ADE and Non-ADE extracts and in lung cells demonstrating that heavy metals are of utmost importance. Glutathione-S-transferase and Heme Oxygenase 1 mRNA levels are induced with ADE PM and reduced by DF and NAC. ADE extracts induced Nrf2 activity and IL-8 mRNA levels significantly more than Non-ADE. NF-κB activity was not detected in any sample. Trace elements and organic constituents in ADE PM2.5 enrich the local environment load, inducing ROS formation and activating antioxidant-signaling pathways increasing pro-inflammatory mediator expressions in lung cells.

Interplay between nuclear factor erythroid 2-related factor 2 and amphiregulin during mechanical ventilation

Mechanical ventilation (MV) elicits complex and clinically relevant cellular responses in the lungs. The current study was designed to define the role of the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2), a major regulator of the cellular antioxidant defense system, in the pulmonary response to MV. Nrf2 activity was quantified in ventilated isolated perfused mouse lungs (IPL). Regulation of amphiregulin (AREG) was investigated in BEAS-2B cells with inactivated Nrf2 or Keap1, the inhibitor of Nrf2, using a luciferase vector with AREG promoter. AREG-dependent Nrf2 activity was examined in BEAS-2B cells, murine precision-cut lung slices (PCLS), and IPL. Finally, Nrf2 knockout and wild-type mice were ventilated to investigate the interplay between Nrf2 and AREG during MV in vivo. Lung functions and inflammatory parameters were measured. Nrf2 was activated in a ventilation-dependent manner. The knockdown of Nrf2 and Keap1 via short hairpin RNA in BEAS-2B cells and an EMSA with lung tissue revealed that AREG is regulated by Nrf2. Conversely, AREG application induced a significant Nrf2 activation in BEAS-2B cells, PCLS, and IPL. The signal transduction of ventilation-induced Nrf2 activation was shown to be p38 MAP kinase-dependent. In vivo ventilation experiments indicated that AREG is regulated by Nrf2 during MV. We conclude that Areg expression is regulated by Nrf2. During high-pressure ventilation, Nrf2 becomes activated and induces AREG, leading to a positive feedback loop between Nrf2 and AREG, which involves the p38 MAPK and results in the expression of cytoprotective genes.

Kaposi's sarcoma-associated herpesvirus induces Nrf2 activation in latently infected endothelial cells through SQSTM1 phosphorylation and interaction with polyubiquitinated Keap1

Nuclear factor erythroid 2-related factor 2 (Nrf2), the cellular master regulator of the antioxidant response, dissociates from its inhibitor Keap1 when activated by stress signals and participates in the pathogenesis of viral infections and tumorigenesis. Early during de novo infection of endothelial cells, KSHV induces Nrf2 through an intricate mechanism involving reactive oxygen species (ROS) and prostaglandin E2 (PGE2). When we investigated the Nrf2 activity during latent KSHV infection, we observed increased nuclear serine-40-phosphorylated Nrf2 in human KS lesions compared to that in healthy tissues. Using KSHV long-term-infected endothelial cells (LTC) as a cellular model for KS, we demonstrated that KSHV infection induces Nrf2 constitutively by extending its half-life, increasing its phosphorylation by protein kinase Cζ (PKCζ) via the infection-induced cyclooxygenase-2 (COX-2)/PGE2 axis and inducing its nuclear localization. Nrf2 knockdown in LTC decreased expression of antioxidant genes and genes involved in KS pathogenesis such as the NAD(P)H quinone oxidase 1 (NQO1), gamma glutamylcysteine synthase heavy unit (γGCSH), the cysteine transporter (xCT), interleukin 6 (IL-6), and vascular endothelial growth factor A (VEGF-A) genes. Nrf2 activation was independent of oxidative stress but dependent on the autophagic protein sequestosome-1 (SQSTM1; p62). SQSTM1 levels were elevated in LTC, a consequence of protein accumulation due to decreased autophagy and Nrf2-mediated transcriptional activation. SQSTM1 was phosphorylated on serine-351 and -403, while Keap1 was polyubiquitinated with lysine-63-ubiquitin chains, modifications known to increase their mutual affinity and interaction, leading to Keap1 degradation and Nrf2 activation. The latent KSHV protein Fas-associated death domain-like interleukin-1β-converting enzyme-inhibitory protein (vFLIP) increased SQSTM1 expression and activated Nrf2. Collectively, these results demonstrate that KSHV induces SQSTM1 to constitutively activate Nrf2, which is involved in the regulation of genes participating in KSHV oncogenesis.

IMPORTANCE

The transcription factor Nrf2 is activated by stress signals, including viral infection, and responds by activating the transcription of cytoprotective genes. Recently, Nrf2 has been implicated in oncogenesis and was shown to be activated during de novo KSHV infection of endothelial cells through ROS-dependent pathways. The present study was undertaken to determine the mechanism of Nrf2 activation during prolonged latent infection of endothelial cells, using an endothelial cell line latently infected with KSHV. We show that Nrf2 activation was elevated in KSHV latently infected endothelial cells independently of oxidative stress but dependent on the autophagic protein sequestosome-1 (SQSTM1), which was involved in the degradation of the Nrf2 inhibitor Keap1. Furthermore, our results indicated that the KSHV latent protein vFLIP participates in Nrf2 activation. This study suggests that KSHV hijacks the host's autophagic protein SQSTM1 to induce Nrf2 activation, thereby manipulating the infected host gene regulation to promote KS pathogenesis.

Secretory function of autophagy in innate immune cells

Eukaryotic cells utilize two main secretory pathways to transport proteins to the extracellular space. Proteins with a leader signal sequence often undergo co-translational transport into the endoplasmic reticulum (ER), and then to the Golgi apparatus before they reach their destination. This pathway is called the conventional secretory pathway. Proteins without signal peptides can bypass this ER-Golgi system and are secreted by a variety of mechanisms collectively called the unconventional secretory pathway. The molecular mechanisms of unconventional secretion are emerging. Autophagy is a conserved bulk degradation mechanism that regulates many intracellular functions. Recent evidence implicates autophagy in the secretory pathway. This review focuses on potential secretory roles of autophagy and how they could modulate the functions of innate immune cells that secrete a wide range of mediators in response to environmental and biological stimuli. We provide a brief overview of the secretory pathways, enumerate the potential mechanistic themes by which autophagy interacts with these pathways and describe their relevance in the context of innate immune cell function.

Long-term aerobic exercise protects against cisplatin-induced nephrotoxicity by modulating the expression of IL-6 and HO-1

Nephrotoxicity is substantial side effect for 30% of patients undergoing cancer therapy with cisplatin and may force them to change or even abandon the treatment. Studies regarding aerobic exercise have shown its efficacy for the treatment of many types of diseases and its capacity to reduce tumors. However, little is known about the impact of physical exercise on cisplatin-induced acute kidney injury (AKI). In the present study, our aim was to investigate the role of physical exercise in AKI induced by cisplatin. We submitted C57Bl6 male mice to seven weeks of chronic exercise on a training treadmill and treated them with single i.p. injection of cisplatin (20 mg/kg) in the last week. Exercise efficacy was confirmed by an increased capillary-to-fiber ratio in the gastrocnemius muscle of exercised groups (EX and CIS-EX). The group submitted to exercise before cisplatin administration (CIS-EX) exhibited less weight loss and decreased serum urea levels compared to the cisplatin group (CIS). Exercise also showed a protective role against cisplatin-induced cell death in the kidney. The CIS-EX group showed a lower inflammatory response, with less TNF and IL-10 expression in the kidney and serum. In the same group, we observed an increase of IL-6 and HO-1 expression in the kidney. Taken together, our results indicate that chronic aerobic exercise is able to attenuate AKI by inducing IL-6 and HO-1 production, which results in lower inflammatory and apoptotic profiles in the kidney.

Impact of altered glycaemia on blood-brain barrier endothelium: an in vitro study using the hCMEC/D3 cell line

BACKGROUND

Cerebrovascular complications involving endothelial dysfunction at the blood-brain barrier (BBB) are central to the pathogenesis of diabetes-related CNS disorders. However, clinical and experimental studies have reported contrasting evidence in relation to the effects of hyperglycemia on BBB permeability and function. Similarly the effect of hypoglycemia on BBB integrity is not well understood. Therefore, we assessed the differential impact of hypo and hyperglycemic conditions on BBB integrity and endothelial function in vitro using hCMEC/D3, a well characterized human brain microvascular endothelial cell line.

METHODS

Parallel monolayers of hCMEC/D3 were exposed to normal, hypo- or hyperglycemic media, containing 5.5, 2.2 or 35 mM D-glucose, respectively. Following 3-24h exposure, the expression and distribution of BBB tight junction (ZO-1 and claudin-5) adherence junction (VE-cadherin) proteins, and glucose transporters as well as inflammatory (VCAM-1) and oxidative stress (Nrf-2) markers were analyzed by immunofluorescence and western blotting. Endothelial release of growth factors and pro-inflammatory cytokines were determined by ELISA. Further, the impact of altered glycemia on BBB permeability was assessed in hCMEC/D3 - astrocyte co-cultures on Transwell supports using fluorescent dextrans (4-70 kDa).

RESULTS

Compared to controls, exposure to hypoglycemia (3 and 24h) down-regulated the expression of claudin-5 and disrupted the ZO-1 localization at cell-cell contacts, while hyperglycemia marginally reduced claudin-5 expression without affecting ZO-1 distribution. Permeability to dextrans (4-10 kDa) and VEGF release at 24h were significantly increased by hypo- and hyperglycemia, although 70 kDa dextran permeability was increased only under hypoglycemic conditions. The expression of SGLT-1 was up-regulated at 24h hypoglycemic exposure while only a modest increase of GLUT-1 expression was observed. In addition, the expression of Nrf-2 and release of interleukin-6 and PDGF-BB, were down-regulated by hypoglycemia (but not hyperglycemia), while both conditions induced a marginal and transient increase in VCAM-1 expression from 3 to 24h, including a significant increase in VE-cadherin expression at 3 h following hyperglycemia.

CONCLUSIONS

In summary, our findings demonstrate a potential impairment of BBB integrity and function by hypo or hyperglycemia, through altered expression/distribution of TJ proteins and nutrient transporters. In addition, hypoglycemic exposure severely affects the expression of oxidative and inflammatory stress markers of BBB endothelium.

An anti-interleukin-2 receptor drug attenuates T- helper 1 lymphocytes-mediated inflammation in an acute model of endotoxin-induced uveitis

The aim of the present study was to evaluate the anti-inflammatory efficacy of Daclizumab, an anti-interleukin-2 receptor drug, in an experimental uveitis model upon a subcutaneous injection of lipopolysaccharide into Lewis rats, a valuable model for ocular acute inflammatory processes. The integrity of the blood-aqueous barrier was assessed 24 h after endotoxin-induced uveitis by evaluating two parameters: cell count and protein concentration in aqueous humors. The histopathology of all the ocular structures (cornea, lens, sclera, choroid, retina, uvea, and anterior and posterior chambers) was also considered. Enzyme-linked immunosorbent assays of the aqueous humor samples were performed to quantify the levels of the different chemokine and cytokine proteins. Similarly, a biochemical analysis of oxidative stress-related markers was also assessed. The inflammation observed in the anterior chamber of the eyes when Daclizumab was administered with endotoxin was largely prevented since the aqueous humor protein concentration substantially lowered concomitantly with a significant reduction in the uveal and vitreous histopathological grading. Th1 lymphocytes-related cytokines, such as Interleukin-2 and Interferon-γ, also significantly reduced with related anti-oxidant systems recovery. Daclizumab treatment in endotoxin-induced uveitis reduced Th1 lymphocytes-related cytokines, such as Interleukin-2 and Interferon gamma, by about 60–70% and presented a preventive role in endotoxin-induced oxidative stress. This antioxidant protective effect of Daclizumab may be related to several of the observed Daclizumab effects in our study, including IL-6 cytokine regulatory properties and a substantial concomitant drop in INFγ. Concurrently, Daclizumab treatment triggered a significant reduction in both the uveal histopathological grading and protein concentration in aqueous humors, but not in cellular infiltration.

IL-6 and related cytokines as the critical lynchpins between inflammation and cancer

Inflammatory responses play pivotal roles in cancer development, including tumor initiation, promotion, progression, and metastasis. Cytokines are now recognized as important mediators linking inflammation and cancer, and are therefore potential therapeutic and preventive targets as well as prognostic factors. The interleukin (IL)-6 family of cytokines, especially IL-6 and IL-11, is highly up-regulated in many cancers and considered as one of the most important cytokine families during tumorigenesis and metastasis. This review discusses molecular mechanisms linking the IL-6 cytokine family to solid malignancies and their treatment.