Modulating Redox Balance Research Articles

Modulation of NRF2/KEAP1 Signaling by Phytotherapeutics in Periodontitis.

Periodontitis affects up to 40% of adults over 60 years old and is a consequence of gingivitis. Periodontitis is characterized by a chronic inflammation, periodontal damage, and alveolar bone resorption. The nuclear factor erythroid 2-related factor 2 (NFE2L2 or NRF2)/Kelch-like ECH-Associated Protein 1 (KEAP1) (NRF2/KEAP1) signaling pathway plays a key role in periodontitis by modulating redox balance and inflammation of the periodontium. However, NRF2 expression is decreased in gingival tissues of patients with periodontitis while oxidative stress is significantly increased in this pathology. Oxidative stress and lipopolysaccharide (LPS) produced by gram-negative bacteria favor the production of inflammatory causing periodontal inflammation and favoring alveolar bone. In this review, we analyzed the current literature regarding the role of natural and synthetic compounds in modulating the NRF2/KEAP1 pathway in in vitro and in vivo models of periodontitis in order to evaluate new potential treatments of periodontitis that can improve the outcome of this disease.

Therapeutic potential of virgin coconut oil in mitigating sodium benzoate- model of male infertility: Role of Nrf2/Hmox-1/NF-kB signaling pathway.

Male infertility is a major public health issue due to increased prevalence, so there is an urgent need for a therapeutic solution. The search for a natural dietary substance that could modulate redox balance and inflammation and protect testicular function is in demand. Virgin Coconut Oil (VCO) has found use in the treatment of diabetes, and cancer owing to the presence of polyphenols. However, there is a dearth of information on its effect on testicular toxicity. The present study investigated VCO as a possible treatment for testicular toxicity in the Sodium Benzoate (SB) model of male infertility by evaluating the oxidative and inflammatory status, circulating hormonal levels, and key sperm indices. Twenty adult male rats were randomly assigned to four groups of 5 rats each and were treated with normal saline, sodium benzoate, sodium benzoate+5% VCO, and sodium benzoate+15% VCO for 30 days respectively. Biochemical analysis of reproductive hormones was assessed. Sperm parameters assessed include sperm function tests and sperm kinematics. One-way analysis of variance (ANOVA) followed by post hoc Tukey tests was performed. 5% VCO reverts the deranged serum reproductive hormones caused by sodium benzoate. 5% VCO was more potent as an antioxidant and anti-inflammatory treatment than 15% VCO. However, both doses prevented SB's effect on the sperm function test and kinematics. VCO-supplemented diet can ameliorate SB-induced testicular toxicity by inhibiting its mechanisms of toxicity that are related to oxidative stress, apoptosis, and inflammation.

Comparative effects of a calcium chelator (BAPTA-AM) and melatonin on cryopreservation-induced oxidative stress and damage in ovarian tissue

Oncology treatments cause infertility, and ovarian tissue cryopreservation and transplantation (OTCT) is the only option for fertility preservation in prepubertal girls with cancer. However, OTCT is associated with massive follicle loss. Here, we aimed to determine the effect of supplementation of slow freezing and vitrification media with BAPTA-AM and melatonin alone and in combination on ovarian tissue viability, reactive oxygen species (ROS) levels, total antioxidant capacity (TAC), and follicular morphology and viability. Our results indicated that BAPTA-AM and melatonin can significantly improve ovarian tissue viability and the TAC/ROS ratio and reduce ROS generation in frozen-thawed ovarian tissues in slow freezing and vitrification procedures. BAPTA-AM was also found to be less effective on TAC compared to melatonin in vitrified ovarian tissue. While supplementation of slow freezing and vitrification media with BAPTA-AM and/or melatonin could increase the percentage of morphologically intact follicles in cryopreserved ovarian tissues, the differences were not significant. In conclusion, supplementation of cryopreservation media with BAPTA-AM or melatonin improved the outcome of ovarian tissue cryopreservation in both vitrification and slow freezing methods. Our data provide some insight into the importance of modulating redox balance and intracellular Ca2+ levels during ovarian tissue cryopreservation to optimize the current cryopreservation methods.

Application of Se-Met to CdTe QDs significantly reduces toxicity by modulating redox balance and inhibiting apoptosis

Cadmium tellurium quantum dots (CdTe QDs) as one of the most widely used QDs have been reported the toxicity and biosafety in recent years, little work has been done to reduce their toxicity however. Based on the mechanisms of toxicity of CdTe QDs on liver target organs such as oxidative stress and apoptosis previously reported by other researchers, we investigated the mechanism of action of trace element selenium (Se) to mitigate the hepatotoxicity of CdTe QDs. The experimental results showed that Se-Met at 40–140 μg L−1 could enhance the function of intracellular antioxidant defense system and the molecular structure of related antioxidant enzymes by reduce the production of ROS by 45%, protecting the activity of antioxidants and up-regulating the expression of selenoproteins with antioxidant functions, Gpx1 increase 225% and Gpx4 upregulated 47%. In addition, Se-Met could alleviate CdTe QDs-induced apoptosis by regulating two apoptosis-inducing factors, as intracellular caspase 3/9 expression levels were reduced by 70% and 87%, decreased Ca2+ concentration, and increased mitochondrial membrane potential measurements. Overall, this study indicates that Se-Met has a significant protective effect on the hepatotoxicity of CdTe QDs. Se-Met can be applied to the preparation of CdTe QDs to inhibit its toxicity and break the application limitation.

Cytosolic malic enzyme and glucose-6-phosphate dehydrogenase modulate redox balance in NSCLC with acquired drug resistance.

Lung cancer cells often show elevated levels of reactive oxygen species (ROS) and nicotinamide adenine dinucleotide phosphate (NADPH). However, the connections between deregulated redox homeostasis in different subtypes of lung cancer and acquired drug resistance in lung cancer have not yet been fully established. Herein, we analyzed different subtypes of lung cancer data reported in the Cancer Cell Line Encyclopedia (CCLE) database, the Cancer Genome Atlas program (TCGA), and the sequencing data obtained from a gefitinib-resistant non-small-cell lung cancer (NSCLC) cell line (H1975GR). Using flux balance analysis (FBA) model integrated with multiomics data and gene expression profiles, we identified cytosolic malic enzyme 1 (ME1) and glucose-6-phosphate dehydrogenase as the major contributors to the significantly upregulated NADPH flux in NSCLC tissues as compared with normal lung tissues, and gefitinib-resistant NSCLC cell line as compared with the parental cell line. Silencing the gene expression of either of these two enzymes in two osimertinib-resistant NSCLC cell lines (H1975OR and HCC827OR) exhibited strong antiproliferative effects. Our findings not only underscored the pivotal roles of cytosolic ME1 and glucose-6-phosphate dehydrogenase in regulating redox states in NSCLC cells but also provided novel insights into their potential roles in drug-resistant NSCLC cells with disturbed redox states.

Nrf2 participates in progression of osteoarthritis through modulating redox balance

Osteoarthritis (OA) is one of the most common degenerative joint diseases associated with aging, obesity and joint trauma, and is always associated with pain, joint deformity and dysfunction. Recent studies have shown that OA is closely related to oxidative stress, which serves as a major cause of chronic inflammation in cartilage, leading to irreversible structural changes in the joint. As a transcription factor, nuclear factor erythroid 2-related factor 2 (Nrf2) plays an important role in the antioxidant system, which regulates the expression of cytoprotective genes to facilitate the elimination of reactive oxygen species (ROS). In this review, we have summarized the dramatic function of oxidative stress in OA pathology, established a complex regulatory network of Nrf2 in OA progression, and aimed to provide new insights into the treatment of OA.

Salinity pretreatment synergies heat shock toxicity in cyanobacterium Anabaena PCC7120.

This study was undertaken to bridge the knowledge gap pertaining to cyanobacteria's response to pretreatment. The result elucidates the synergistic effect of pretreatment toxicity in cyanobacterium Anabaena PCC7120 on morphological and biochemical attributes. Chemical (salt) and physical (heat) stress-pretreated cells exhibited significant and reproducible changes in terms of growth pattern, morphology, pigments, lipid peroxidation, and antioxidant activity. Salinity pretreatment showed more than a five-fold decrease in the phycocyanin content but a six-fold and five-fold increase in carotenoid, lipid peroxidation (MDA content), and antioxidant activity (SOD and CAT) at 1 h and on 3rd day of treatment, respectively, giving the impression of stress-induced free radicals that are scavenged by antioxidants when compared to heat shock pretreatment. Furthermore, quantitative analysis of transcript (qRT-PCR) for FeSOD and MnSOD displayed a 3.6- and 1.8-fold increase in salt-pretreated (S-H) samples. The upregulation of transcript corresponding to salt pretreatment suggests a toxic role of salinity in synergizing heat shock. However, heat pretreatment suggests a protective role in mitigating salt toxicity. It could be inferred that pretreatment enhances the deleterious effect. However, it further showed that salinity (chemical stress) augments the damaging effect of heat shock (physical stress) more profoundly than physical stress on chemical stress possibly by modulating redox balance via activation of antioxidant responses. Our study reveals that upon pretreatment of heat, the negative effect of salt can be mitigated in filamentous cyanobacteria, thus providing a foundation for improved cyanobacterial tolerance to salt stress.

Consumption of golden berries (Physalis peruviana L.) might reduce biomarkers of oxidative stress and alter gut permeability in men without changing inflammation status or the gut microbiota

Golden berry (Physalis peruviana) is a tropical fruit rich in antioxidants that has been proposed to be able to control the lipid profile in hypercholesterolemic patients. Dyslipidemia is an independent risk factor for cardiometabolic diseases. The gut microbiota is strongly associated with cardiometabolic risk and is involved in redox balance, intestinal permeability, and inflammation. However, the impacts of golden berry on some of these factors, including the human gut microbiota, have never been tested, and there are no tools for compliance monitoring or dietary intake assessment regarding nutritional interventions with this fruit. In the pre-post quasi-experimental nutritional intervention presented here, 18 adult men (27–49 years old) consumed golden berries (Dorada variety) for three weeks. We evaluated putative biomarkers of exposure through an untargeted metabolomics approach (liquid chromatography-mass spectrometry LC-MS), quantified the biomarkers of oxidative stress, gut permeability, and inflammation in plasma, and assessed the effects of fruit intake on the gut microbiota through 16S rRNA gene sequencing of feces (Illumina MiSeq V2). First, syringic acid and kaempferol were identified as putative biomarkers of golden berry consumption. Intervention with this fruit promoted physiological changes in the participants after three weeks, reducing the level of the oxidative stress marker 8-isoprostane (-148 pg/ml; 36.1 %; p = 0.057) and slightly altering gut permeability by increasing the plasma levels of LBP (2.91 µg/ml; 54.6 %; p = 0.0005) and I-FABP (0.15, 14.7 %, p = 0.04) without inducing significant inflammation; i.e., the levels of IL-1β, TNF-α and IL-8 changed by 0.7 (2.0 %), −4.0 (-9.6 %) and −0.4 (-1.8 %) pg/ml, respectively. Notably, the consumption of golden berries did not affect the gut microbiota of the individuals consistently but instead shifted it in a personalized manner. The compositions of the gut microbiota of a given individual at the end of intervention and one month after the end of intervention were statistically more similar to their own baseline than to a corresponding sample from a different individual. This intervention identified putative biomarkers of golden berry intake along with potential benefits of its consumption relevant to cardiometabolic disease risk reduction. Golden berries are likely to positively modulate redox balance, although this effect must be proven in a future controlled clinical trial.

Arctiin-reinforced antioxidant microcarrier antagonizes osteoarthritis progression

Loss of extracellular matrix (ECM) of cartilage due to oxidative stress injury is one of the main characteristics of osteoarthritis (OA). As a bioactive molecule derived from the traditional Chinese Burdock, arctiin exerts robust antioxidant properties to modulate redox balance. However, the potential therapeutic effects of arctiin on OA and the underlying mechanisms involved are still unknown. Based on the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP) tool, Burdock-extracted small molecule arctiin was identified as a potential anti-arthritic component. In vitro, treatment using arctiin rescued the interleukin (IL)-1β-induced activation of proteinases and promoted the cartilage ECM synthesis in human chondrocytes. In vivo, intraperitoneal injection of arctiin ameliorated cartilage erosion and encountered subchondral bone sclerosis in the post-traumatic OA mice. Transcriptome sequencing uncovered that arctiin-enhanced cartilage matrix deposition was associated with restricted oxidative stress. Mechanistically, inhibition of nuclear factor erythroid 2-related factor 2 (NRF2) abolished arctiin-mediated anti-oxidative and anti-arthritic functions. To further broaden the application prospects, a gellan gum (GG)-based bioactive gel (GG-CD@ARC) encapsulated with arctiin was made to achieve long-term and sustained drug release. Intra-articular injection of GG-CD@ARC counteracted cartilage degeneration in the severe (12 weeks) OA mice model. These findings indicate that arctiin may be a promising anti-arthritic agent. Furthermore, GG-modified bioactive glue loaded with arctiin provides a unique strategy for treating moderate to severe OA.Graphical

Neonatal Exposure to Titanium Dioxide Nanoparticles Modulates the Redox Balance in Infantile and Adult Female Rats

Objectives: The aim of our study was to determine a possible relationship between the redox state of the organism and the exposure to TiO2 Nanoparticles (NPs). Design and methods: TiO2 NPs (1% or 10% LD50 TiO2) were intraperitoneally administered to female Wistar rats from the Postnatal Day 4 (PND4) to PND7. Rats were sacrificed on the PND15 (infantile rats) or after the PND220 (adult rats). In plasma, Antioxidant Capacity (TEAC), concentration of protein carbonyls and lipoperoxides were measured. Hemolysates were used to determine the changes in catalase, Glutathione Peroxidase (GPx) and Superoxide Dismutase (SOD) activities. Results: Young rats: 1% and 10% LD50 TiO2 induced the decrease in TEAC, lipoperoxide levels and Gluthione Peroxidase (GPx) activities and higher Superoxide Dismutase (SOD) activities in infantile rats, compared to controls. Adults: Significantly lower lipoperoxide levels, higher SOD and GPx activities were found in adults compared to young rats. 1% LD50 TiO2 significantly increased TEAC value and reduced SOD and GPX activities, but 10% LD50 TiO2 reduced TEAC compared to controls. Conclusion: Our results demonstrate that neonatal exposure to TiO2 NPs may modulate redox balance in female rats depending on the age, which might lead to alterations of their physiological functions.

Antioxidant and anti‑inflammatory mechanisms of action of astaxanthin in cardiovascular diseases (Review).

Cardiovascular diseases are the most common cause of mortality worldwide. Oxidative stress and inflammation are pathophysiological processes involved in the development of cardiovascular diseases; thus, anti-inflammatory and antioxidant agents that modulate redox balance have become research targets so as to evaluate their molecular mechanisms of action and therapeutic properties. Astaxanthin, a carotenoid of the xanthophyll group, has potent antioxidant properties due to its molecular structure and its arrangement in the plasma membrane, factors that favor the neutralization of reactive oxygen and nitrogen species. This carotenoid also has prominent anti-inflammatory activity, possibly interrelated with its antioxidant effect, and is also involved in the modulation of lipid and glucose metabolism. Considering the potential beneficial effects of astaxanthin on cardiovascular health evidenced by preclinical and clinical studies, the aim of the present review was to describe the molecular and cellular mechanisms associated with the antioxidant and anti-inflammatory properties of this carotenoid in cardiovascular diseases, particularly atherosclerosis. The beneficial properties and safety profile of astaxanthin indicate that this compound may be used for preventing progression or as an adjuvant in the treatment of cardiovascular diseases.

The Alleviative Effects of Salicylic Acid on Physiological Indices and Defense Mechanisms of Maize (Zea Mays L. Giza 2) Stressed with Cadmium

The present study evaluated the physiological and biochemical mechanisms through which exogenous salicylic acid (SA) mitigates cadmium (Cd) stress in maize. The different concentrations of Cd included 0, 5, 10 µM CdCl2.3H2O. Half of plants received salicylic acid as a soil drench. Results showed that Cd exposure reduced chlorophyll contents, chlorophyll fluorescence, photosynthetic rate and activity of catalase (CAT). However, Cd stress enhanced non-photochemical quenching (NPQ), the production of malondialdehyde (MDA) and activities of key antioxidant enzymes superoxide dismutase (SOD), ascorbate peroxidase (APX), guaiacol peroxidase (POD). The increased activities of antioxidant enzymes and concentration of MDA were reduced by exogenous application of SA as a soil drench. Our research proves that SA, as a novel endogenous plant hormone exerts beneficial physiological effects on plants as it has a dual role in scavenging active oxygen species (AOS) and modulating redox balance to enhance photosynthetic performance in cadmium-stressed maize plants. It was concluded that SA improved plant tolerance under Cd contamination and may have alleviated the inhibitory effect of Cd on photosynthesis by protecting maize plants against oxidative damage as indicated by the marked decline in net photosynthetic rates, quantum yield and chlorophyll content as well as alteration of antioxidants activity and accumulation of MDA. Collectively, results of the present study provide an insight into the alleviative role of SA in Cd-stressed maize and propose SA as a potential candidate in mitigating Cd toxicity.

Protoflavone-Chalcone Hybrids Exhibit Enhanced Antitumor Action through Modulating Redox Balance, Depolarizing the Mitochondrial Membrane, and Inhibiting ATR-Dependent Signaling.

Hybrid compounds combine fragments with complementary targets to achieve a common pharmacological goal. This approach represents an increasingly popular strategy for drug discovery. In this work, we aimed to design antitumor hybrid compounds based on an inhibitor of ataxia-telangiectasia and Rad3-related protein (ATR)-dependent signaling, protoapigenone, and a pro-oxidant ferrocene or chalcone fragment. Four new triazole-coupled hybrids were prepared. The compounds were cytotoxic against human breast cancer cell lines in vitro, showing IC50 values in the sub-micromolar range. The nature of interactions between relevant fragments of the hybrids was evaluated by the Chou–Talalay method. Experimental combination treatment with the fragments showed additive effects or slight/moderate synergism, while strong synergism was observed when the fragments were virtually combined into their hybrids, suggesting a relevant pharmacological benefit of the coupling. All hybrids were strong inhibitors of the ATR-mediated activation of Chk1, and they interfered with the redox balance of the cells leading to mitochondrial membrane depolarization. Additionally, they induced late apoptosis and primary necrosis in MDA-MB-231 and MCF-7 breast cancer cells, respectively. Our results demonstrate that coupling the ATR-dependent signaling inhibitor protoflavone with a pro-oxidant chalcone dramatically increases the antitumor activity compared with either fragment alone. Such compounds may offer an attractive novel strategy for the treatment of various cancers.

The hepatoprotective effect of Cheral as anti-oxidant and anti-inflammation on mice (Mus musculus) with breast cancer

Introduction: Recent studies have reported that breast cancer may affect the physiology of other organs, including oxidative stress in the liver. On the other hand, some agents such as white turmeric (Curcuma longa) and Meniran (Phyllanthus niruri) seem to maintain redox stability and immunomodulation. Both of them are combined into Cheral potion. This study was aimed to investigate the Cheral efficacy in modulating oxidative stress based on Nuclear factor erythroid 2-related factor 2 (Nrf2), HEME OXIGenase (HO), and superoxide dismutase (SOD) levels as well as pro-inflammatory cytokines under breast cancer condition in vivo. Methods: Nrf2, HO, and SOD from hepatocytes, and tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) from splenocytes were measured by flow cytometry after 14 days of Cheral administration. Results: The results showed that mice model for breast cancer underwent oxidative stress denoted by high levels of HO, and SOD accompanied by increased levels of TNF-α and IFN-γ in the cancer group compared to normal healthy group (P<0.05). In contrast, Cheral treatment was able to modulate redox balance by declining levels of HO, SOD, TNF-α, and IFN-γ, but not Nrf2, compared to cancer group (P<0.05). Conclusion: The results showed that breast cancer could alter the host’s physiology, including liver oxidative stress. The levels of TNF-α and IFN-γ might contribute to regulation of redox balance in the liver. However, Cheral has potency as an alternative therapeutic agent to reduce oxidative stress in the liver under breast cancer condition.

Abstract 2894: Overcoming intrinsic resistance to BRAF-inhibitors by modulating redox balance inBRAF-mutated melanoma cells

Abstract Post-resistant tumor analyses or static measurements provide most of our current knowledge of tumor recurrence. Unfortunately, these studies neither elucidate critical events that precede resistance nor explain the dynamics of drug response in cancer cells. Filling this knowledge gap may engender key advances in cancer therapy. Therefore, we coupled single-cell time-lapse microscopy, bioinformatics, and mathematical modeling to study the dynamics of drug response in BRAF-mutated melanoma cells. We recently reported a novel non-quiescent idling state that melanoma cells exhibit under continued drug exposure. Although Idling cells exhibit a constant population size, they continue to divide and die at the level of the single cell. We speculate that idling state, primed to acquire resistance, could be a new type of drug tolerance, and may constitute the bulk of minimum residual disease (MRD)often seen in the clinic in remission. Melanoma cells we considered, exhibited heterogeneous responses prior to convergence to idling state. These differential responses in melanoma can be defined within a mathematical framework of epigenetic landscape: initial heterogeneity reflects an early re-equilibration among distinct phenotypic basins while idling is a final equilibrated state. Thus, describing the molecular signatures that define basins in BRAF-mutated melanoma landscape, both drug-naïve and drug-induced, would provide rational strategies to alter the landscape and enhance the clinical benefits. To this end, we utilized single-cell-derived clones to find gene-signatures that correlate to drug-sensitivity and discovered that drug-naïve landscape could be defined with respect to distinct redox metabolism. We further confirmed and validated these signatures in CCLE dataset across a range of BRAF-mutated melanoma cells. Specifically, the antioxidants such as NADPH and GSH provide an early survival advantage to melanoma cells under BRAF-inhibition. We show that modulating expression of these metabolic genes changes the initial landscape, and synergizes with BRAF-inhibitors. The enhanced effects of combination can be mitigated by antioxidants specific to glutathione redox balance. These observations suggest that disruption of redox balance, in combination with BRAF-inhibition, may improve the outcomes of BRAF-targeted therapy. Additionally, this strategy will maximize initial cell killing, and hence reduce the number of cells that constitute MRD or idling state. Taken together, our work provides a unifying view of how melanomas respond to BRAF-inhibition and suggest that targeted landscaping is a rational way to suppress both an initial tumor and idling cells. Citation Format: B. Bishal Paudel, Leonard A. Harris, Keisha N. Hardeman, Corey E. Hayford, Christian T. Meyer, Arwa A. Abugable, Darren R. Tyson, Joshua P. Fessel, Vito Quaranta. Overcoming intrinsic resistance to BRAF-inhibitors by modulating redox balance inBRAF-mutated melanoma cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2894.

Modulation of the cell growth by Aloe Vera extract and hydrogen peroxide

Reactive oxygen species (ROS), reactive nitrogen species, and their counterpart antioxidant agents are essential for physiological signaling, while imbalances between oxidants and antioxidants may provoke pathological reactions causing a range of diseases including cancer. In addition, ROS can stimulate signal transduction pathways and lead to activation of key transcription factors such as Nrf2 and NF-κB modulating cell growth and redox balance [1]. The well-known medical plant Aloe vera contains an abundance of antioxidants, which are capable of neutralising ROS [2]. This work evaluates the effects of the genuine Aloe vera extract (AV) on human cells in vitro in respect to the toxic effects of hydrogen peroxide. After propagating Aloe vera for 1 year in 0.5 kg plastic pots, the first fully developed leaf, fourth from the top, was harvested and subjected to biochemical tests for determination of vitamin C, carotenoids and total soluble phenolic content, while total antioxidant capacity of the plant extract was analysed using Brand-Williams method [3]. Afterwards, four different human cell lines, notably HeLa (human cervical cancer), HMEC (human microvascular endothelial cells), HaCat (human keratinocytes) and HOS (human osteosarcoma) were treated with 2 concentrations of AV for 1 hour after one hour pre-treatment with ranging concentrations of H2O2, thus inducing oxidative stress. The viability of the cells was determined by an MTT-based vitality assay, EZ4U (Biomedica, Vienna, Austria). The plant extract expressed strong antioxidant capacities (1.1 mmol of Trolox eq./g FW), mostly likely due to the combined effects of its antioxidants ingredients. However, while H2O2 inhibited in a concentration dependent manner the growth of all cell lines except HOS, the extract of AV did not show any particular effects except a slight stimulation of the HeLa and HMEC cells. We may assume that antioxidants of the plant extract are not involved in the observed growth modifying effects on the different cell lines used. More likely, some components of the plant extract could interfere with the cellular antioxidants and redox signalling and its effects together with hydrogen peroxide. The above actions of AV confirmed that it can potentially act as relatively safe natural source of medical remedies since there were no toxic effects observed, while further studies on the mechanisms of its actions are needed.

P-367 - PPARγ phosphorylation at Ser186 regulates metabolic inflammation via modulating redox balance in adipocyte tissue macrophages

Obesity is a chronic inflammation in which inflammatory adipocyte tissue macrophages (ATMs) are regarded as prominent players. Our previous works have suggested that PPARg, a master regulator of adipogenesis, modulates macrophage differentiation and polarization, whereby impacts metabolic inflammation. Given that PPARg activities are fine-tuned by its post-translational modifications, we have been trying to identify the new modification sites of PPARg in adipose tissue macrophages. We isolated ATMs and analyzed PPARg phosphorylation with phosphoproteomics and other related techniques. The results demonstrate that PPARg phosphorylation in ATMs was gradually increased along with the obesity progression, which induced the progressive metabolic inflammation. It was noteworthy that PPARg 186 phosphorylation was found to modulate GSH/GSSG ratio in ATMs, which resulted in modified fatty acid metabolic pathway, dysregulated mitochondrial homeostasis, and ultimately aggressive inflammatory responses, especially TNFa expression. By combined using chemical screen system and bioactivity analysis, we found that small molecule SWX12 could block PPARg phosphorylation and then regulate intracellular redox balance in ATMs, which was proven to be related with local inflammation reduction.

Loss of c-Met signaling sensitizes hepatocytes to lipotoxicity and induces cholestatic liver damage by aggravating oxidative stress.

Recent studies confirmed a critical importance of c-Met signaling for liver regeneration by modulating redox balance. Here we used liver-specific conditional knockout mice (MetKO) and a nutritional model of hepatic steatosis to address the role of c-Met in cholesterol-mediated liver toxicity. Liver injury was assessed by histopathology and plasma enzymes levels. Global transcriptomic changes were examined by gene expression microarray, and key molecules involved in liver damage and lipid homeostasis were evaluated by Western blotting. Loss of c-Met signaling amplified the extent of liver injury in MetKO mice fed with high-cholesterol diet for 30days as evidenced by upregulation of liver enzymes and increased synthesis of total bile acids, aggravated inflammatory response and enhanced intrahepatic lipid deposition. Global transcriptomic changes confirmed the enrichment of networks involved in steatosis and cholestasis. In addition, signaling pathways related to glutathione and lipid metabolism, oxidative stress and mitochondria dysfunction were significantly affected by the loss of c-Met function. Mechanistically, exacerbation of oxidative stress in MetKO livers was corroborated by increased lipid and protein oxidation. Western blot analysis further revealed suppression of Erk, NF-kB and Nrf2 survival pathways and downstream target genes (e.g. cyclin D1, SOD1, gamma-GCS), as well as up-regulation of proapoptotic signaling (e.g. p53, caspase 3). Consistent with the observed steatotic and cholestatic phenotype, nuclear receptors RAR, RXR showed increased activation while expression levels of CAR, FXR and PPAR-alpha were decreased in MetKO. Collectively, our data provide evidence for the critical involvement of c-Met signaling in cholesterol and bile acids toxicity.

Effect of arbuscular mycorrhizal fungi inoculation on cold stress-induced oxidative damage in leaves of Elymus nutans Griseb

To investigate the effect of arbuscular mycorrhizal fungi (AMF) inoculation and short-term cold exposer on Elymus nutans Griseb, 45day old seedlings of two cultivars, Zhengdao (ZD) and Kangma (KM), were subjected to a 5day cold treatment after inoculated with Glomus mosseae. The effects of AMF on the physiology of the two cultivars were determined, and we were especially interested in oxidative indexes under cold stress. Accumulation of reactive oxygen species (ROS), including superoxide and hydrogen peroxide, was very high in cold-stressed plants and caused lipid peroxidation in membranes, which measured as relative electrolyte leakage (REL), malondialdehyde (MDA) content. Less oxidative damage was detected in AMF colonized plants, which was associated with higher activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR). Mycorrhizal inoculum application promoted plant growth and enhanced the level of chlorophyll and antioxidant compounds such as glutathione and soluble sugars. We also measured the extent of mycorrhizal colonization. These protective mechanisms were found to be more efficient in temperature-tolerant KM than temperature-sensitive ZD. Overall, we suggest that AMF inoculation can improve plant resistance to cold stress in E. nuatans seedlings by directly scavenging ROS and by modulating redox balance and other defense mechanisms.

The regulatory effect of melatonin on physiological, biochemical and molecular parameters in cold-stressed wheat seedlings

We investigated the possible mediatory role of melatonin in protecting wheat plants from cold stress. Ten-day-old wheat seedlings were pretreated with 1 mmol l−1 melatonin for 12 h and subsequently exposed to stress conditions at 5/2 °C (day/night) for 3 days. Cold stress caused serious reductions in leaf surface area, water content, and photosynthetic pigment content, whereas melatonin application attenuated these reductions. Accumulation of reactive oxygen species (ROS), including superoxide and hydrogen peroxide, was very high in cold-stressed plants and caused lipid peroxidation in membranes. Concomitantly, ROS damaged the DNA profile and negatively influenced expression and/or activity of many enzymes, including RuBisCo. When compared to controls, cold-stressed plants had higher activities of the antioxidant enzymes superoxide dismutase, guaicol peroxidase, ascorbate peroxidase, and glutathione reductase and higher levels of the antioxidant compounds total ascorbate, reduced ascorbate, total glutathione, reduced glutathione, and phenolic substances; however, this elevation could not cope with the destructive effects of cold stress. Melatonin-pretreated plants exhibited greater increases in these parameters comparison with untreated cold-stressed plants. Isozyme bands monitored in native gel and RuBisCo expression supported these changes. Also, due to the cold-induced increase in dehydroascorbate and oxidized glutathione, the corrupted redox status in the cell was ameliorated by melatonin application. Similarly, levels of the osmoprotectants total soluble protein, carbohydrate, and proline were also increased by cold stress; however, melatonin-applied seedlings had a higher content of these solutes in comparison to untreated cold-stressed plants. We suggest that melatonin can improve plant resistance to cold stress in wheat seedlings by directly scavenging ROS and by modulating redox balance and other defence mechanisms.