Maillard reaction, mitochondria and oxidative stress: potential role of antioxidants

Methylglyoxal activates transient receptor potential A1/V1 via reactive oxygen species in the spinal dorsal horn

Methylglyoxal (MGO), a highly reactive dicarbonyl metabolite of glucose primarily formed during the glycolytic pathway, is a precursor of advanced glycation end-products (AGEs). Recently, numerous studies have shown that MGO accumulation can cause pain and hyperalgesia. However, the mechanism through which MGO induces pain in the spinal dorsal horn remains unclear. The present study investigated the effect of MGO on spontaneous excitatory postsynaptic currents (sEPSC) in rat spinal dorsal horn neurons using blind whole-cell patch-clamp recording. Perfusion of MGO increased the frequency and amplitude of sEPSC in spinal horn neurons in a concentration-dependent manner. Additionally, MGO administration increased the number of miniature EPSC (mEPSC) in the presence of tetrodotoxin, a sodium channel blocker. However, 6-cyano-7-nitroqiunocaline-2,3-dione (CNQX), an AMPA/kainate receptor antagonist, blocked the enhancement of sEPSC by MGO. HC-030031, a TRP ankyrin-1 (TRPA1) antagonist, and capsazepine, a TRP vanilloid-1 (TRPV1) antagonist, inhibited the action of MGO. Notably, the effects of MGO were completely inhibited by HC-030031 and capsazepine. MGO generates reactive oxygen species (ROS) via AGEs. ROS also potentially induce pain via TRPA1 and TRPV1 in the spinal dorsal horn. Furthermore, we examined the effect of MGO in the presence of N-tert-butyl-α-phenylnitrone (PBN), a non-selective ROS scavenger, and found that the effect of MGO was completely inhibited. These results suggest that MGO increases spontaneous glutamate release from the presynaptic terminal to spinal dorsal horn neurons through TRPA1, TRPV1, and ROS and could enhance excitatory synaptic transmission.

Antioxidant Activity, Metabolism, and Bioavailability of Polyphenols in the Diet of Animals

As the world’s population grows, so does the need for more and more animal feed. In 2006, the EU banned the use of antibiotics and other chemicals in order to reduce chemical residues in food consumed by humans. It is well known that oxidative stress and inflammatory processes must be combated to achieve higher productivity. The adverse effects of the use of pharmaceuticals and other synthetic compounds on animal health and product quality and safety have increased interest in phytocompounds. With the use of plant polyphenols in animal nutrition, they are gaining more attention as a supplement to animal feed. Livestock feeding based on a sustainable, environmentally friendly approach (clean, safe, and green agriculture) would also be a win–win for farmers and society. There is an increasing interest in producing healthier products of animal origin with a higher ratio of polyunsaturated fatty acids (PUFAs) to saturated fatty acids by modulating animal nutrition. Secondary plant metabolites (polyphenols) are essential chemical compounds for plant physiology as they are involved in various functions such as growth, pigmentation, and resistance to pathogenic organisms. Polyphenols are exogenous antioxidants that act as one of the first lines of cell defense. Therefore, the discoveries on the intracellular antioxidant activity of polyphenols as a plant supplement have contributed significantly to the improvement of antioxidant activity, as polyphenols prevent oxidative stress damage and eliminate excessively produced free radicals. To achieve animal welfare, reduce stress and the need for medicines, and increase the quality of food of animal origin, the addition of polyphenols to research and breeding can be practised in part with a free-choice approach to animal nutrition.

Metabolomics reveals the defense mechanism of histidine supplementation on high-salt exposure-induced hepatic oxidative stress

AIMS

This study mainly evaluated the protective mechanism of histidine against the hepatic oxidative stress after high-salt exposure (HSE) through combined analysis of non-targeted metabolomics and biological metabolic networks.

MATERIALS AND METHODS

Dahl salt-sensitive (SS) rats were fed with normal-salt diet or HSE ± histidine in addition to drinking water for 14 days. Gas chromatography-mass spectrometry was used to analyze the hepatic metabolites. The metabolic profile was analyzed by SIMCA-14.1, the metabolic correlation network was performed using Gephi-0.9.2, and pathway enrichment was analyzed using MetaboAnalyst 5.0 online website.

KEY FINDINGS

Results indicated that HSE disturbed the hepatic metabolic profile, generated abnormal liver metabolism and exacerbated oxidative stress. Histidine supplementation significantly reversed the hepatic metabolic profile. Of note, 14 differential metabolic pathways were enriched after histidine supplementation, most of which played an important role in ameliorating redox and nitric oxide (NO) metabolism. Histidine administration decreased the levels of hydroperoxide and malondialdehyde, and increased the activities of antioxidant enzymes (Catalase, Superoxide Dismutase, Glutathione S-transferase and Glutathione reductases). Histidine effectively enhanced the endogenous synthesis of glutathione by increasing the levels of glutamate and cysteine, thereby enhancing the antioxidant capacity of the glutathione system. After histidine administration, lysine, glutamate, and hypotaurine owned a higher metabolic centrality in the correlation network. In addition, histidine could also effectively increase the endogenous synthesis of NO by enhancing the _L-arginine/NO pathway.

SIGNIFICANCE

This study offers new insights into the metabolic mechanisms underlying the antioxidant protective effect of histidine on the liver.

Research Advances on the Damage Mechanism of Skin Glycation and Related Inhibitors

Our skin is an organ with the largest contact area between the human body and the external environment. Skin aging is affected directly by both endogenous factors and exogenous factors (e.g., UV exposure). Skin saccharification, a non-enzymatic reaction between proteins, e.g., dermal collagen and naturally occurring reducing sugars, is one of the basic root causes of endogenous skin aging. During the reaction, a series of complicated glycation products produced at different reaction stages and pathways are usually collectively referred to as advanced glycation end products (AGEs). AGEs cause cellular dysfunction through the modification of intracellular molecules and accumulate in tissues with aging. AGEs are also associated with a variety of age-related diseases, such as diabetes, cardiovascular disease, renal failure (uremia), and Alzheimer's disease. AGEs accumulate in the skin with age and are amplified through exogenous factors, e.g., ultraviolet radiation, resulting in wrinkles, loss of elasticity, dull yellowing, and other skin problems. This article focuses on the damage mechanism of glucose and its glycation products on the skin by summarizing the biochemical characteristics, compositions, as well as processes of the production and elimination of AGEs. One of the important parts of this article would be to summarize the current AGEs inhibitors to gain insight into the anti-glycation mechanism of the skin and the development of promising natural products with anti-glycation effects.

Glycation-induced age-related illnesses, antiglycation and drug delivery strategies

OBJECTIVES

Ageing is a major cause of multiple age-related diseases. Several mechanisms have been reported to contribute to these abnormalities including glycation, oxidative stress, the polyol pathway and osmotic stress. Glycation, unlike glycosylation, is an irregular biochemical reaction to the formation of active advanced glycation end-products (AGEs), which are considered to be one of the causes of these chronic diseases. This study provides a recent and comprehensive review on the possible causes, mechanisms, types, analytical techniques, diseases and treatments of the toxic glycation end products.

KEY FINDINGS

Several mechanisms have been found to play a role in generating hyperglycaemia-induced oxidative stress including an increase in the levels of reactive oxygen species (ROS), increase in the levels of AGEs, binding of AGEs and their receptors (RAGE) and the polyol pathway and thus have been investigated as promising novel targets.

SUMMARY

This review focuses on the key mechanisms attributed to cumulative increases of glycation and pathological RAGE expression as a significant cause of multiple age-related diseases, and reporting on different aspects of antiglycation therapy as a novel approach to managing/treating age-related diseases. Additionally, historical, current and possible future antiglycation approaches will be presented focussing on novel drug delivery methods.

Properties of Cephalopod Skin Ommochromes to Inhibit Free Radicals, and the Maillard Reaction and Retino-Protective Mechanisms in Cellular Models Concerning Oxidative Stress, Angiogenesis, and Inflammation

Ommochromes are pigments of invertebrates that exhibit oxidative stress protection. The aim of this study was to investigate ommochromes extracted from cephalopod’s skin for their ability to inhibit age-related-macular degeneration (AMD)-related factors such as H₂O₂-induced and iron-dependent oxidative stress (ferroptosis and erastin), accumulation of advanced glycation end-products (AGEs), as well as vascular endothelial growth factor (VEGF), and inflammatory cytokines (interleukin 6 and interleukin 8) secretion. As cell systems, we used primary porcine retinal pigment epithelium (RPE), human retinal pigment epithelium cell line ARPE-19 and uveal melanoma cell line OMM-1. In vitro, ommochromes produced an antiglycation effect by the inhibition of fructosylation reaction. The ommochromes showed protective effects against erastin- induced cell death in ARPE-19. In addition, in long-term stimulation (7 days) ommochromes decreased constitutively secreted VEGF, as well as interleukin 6 and interleukin 8 induced by Poly I:C in primary RPE. No relevant effects were detected in OMM-1 cells. The effects are dependent on the cell system, time of exposition, and concentration. This substance is of interest for further research concerning age-related macular degeneration.

Preventing Oxidative Stress in the Liver: An Opportunity for GLP-1 and/or PASK

The liver’s high metabolic activity and detoxification functions generate reactive oxygen species, mainly through oxidative phosphorylation in the mitochondria of hepatocytes. In contrast, it also has a potent antioxidant mechanism for counterbalancing the oxidant’s effect and relieving oxidative stress. PAS kinase (PASK) is a serine/threonine kinase containing an N-terminal Per-Arnt-Sim (PAS) domain, able to detect redox state. During fasting/feeding changes, PASK regulates the expression and activation of critical liver proteins involved in carbohydrate and lipid metabolism and mitochondrial biogenesis. Interestingly, the functional inactivation of PASK prevents the development of a high-fat diet (HFD)-induced obesity and diabetes. In addition, PASK deficiency alters the activity of other nutrient sensors, such as the AMP-activated protein kinase (AMPK) and the mammalian target of rapamycin (mTOR). In addition to the expression and subcellular localization of nicotinamide-dependent histone deacetylases (SIRTs). This review focuses on the relationship between oxidative stress, PASK, and other nutrient sensors, updating the limited knowledge on the role of PASK in the antioxidant response. We also comment on glucagon-like peptide 1 (GLP-1) and its collaboration with PASK in preventing the damage associated with hepatic oxidative stress. The current knowledge would suggest that PASK inhibition and/or exendin-4 treatment, especially under fasting conditions, could ameliorate disorders associated with excess oxidative stress.

Low Birth Weight Disturbs the Intestinal Redox Status and Mitochondrial Morphology and Functions in Newborn Piglets

Simple Summary

Low birth-weight piglets normally have a higher growth retardation and are more prone to disease such as diarrhea compared to NBW piglets, which are strongly associated with intestinal health, body redox status and mitochondrial morphology and function. The present study showed that low birth-weight piglets exhibited abnormal intestinal development and impaired intestinal barrier function and redox status when compared to normal- birth-weight piglets. Furthermore, we found that the impaired mitochondrial structure and functions may be one of the main causes of intestinal dysfunction in low birth-weight piglets. These results provided insights for the mechanisms of intestinal dysfunction in low birth-weight piglets.

Abstract

Low birth-weight (LBW) neonates exhibit a lower growth rate and impaired intestinal development. However, the reasons for abnormal development of small intestine in LBW piglets have not been widely studied. The present study focused on the redox status and mitochondrial morphology and functions of the small intestine in LBW newborn piglets. Ten newborn normal birth-weight (NBW) piglets and LBW piglets from 10 primiparous sows with the same parturition day were selected and sampled immediately without sucking colostrum. The small intestine tissues were collected and measured. Compared with NBW newborn piglets, LBW newborn piglets had a significantly decreased length and weight of the small intestine (p < 0.05) as well as the villus height/crypt depth (V/C) index in the jejunum (p < 0.05). Furthermore, LBW piglets had a lower gene expression of tight junction protein zonula occluden-1 (ZO1), claudin 1, antioxidant enzyme catalase (CAT), glutathione peroxidase (GPX) and heme oxygenase-1 (HO-1) in jejunum (p < 0.05). Meanwhile, LBW induced mitochondrial vacuolation and significantly decreased the mRNA expression of PPARγ coactivator-1α (PGC-1α) (p < 0.05) and tended to decrease the expression of cytochrome coxidase IV (Ccox IV) (p = 0.07) and cytochrome C (Cytc) (p = 0.08). In conclusion, LBW newborn piglets showed an abnormal development of the small intestine and disturbed redox status, and this may be caused by impaired morphology and the functions of mitochondria in the jejunum.

Novel Extract from Beetle Ulomoides dermestoides: A Study of Composition and Antioxidant Activity

A biologically active extract from the darkling beetle Ulomoides dermestoides was obtained using the electro-pulse plasma dynamic extraction method. The beetle water extract contained a complex of antioxidant substances such as antioxidant enzymes and nonprotein antioxidants, as well as a complex of heat shock antistress proteins. This determines the rather high antioxidant activity of the aqueous extract of the beetle, i.e., 1 mg of dry matter/mL of the extract has an equivalent antioxidant activity to 0.2 mM Trolox (a water-soluble analog of vitamin E). It was shown that the beetle extract can lead to a 25-30% increase in the average lifespan of nematode Caenorhabditiselegans, under normal conditions, and a 12-17% increase under conditions of oxidative stress (with paraquat), and significantly inhibits the fructosylation reaction of serum albumin. Therefore, the beetle aqueous extract shows promise as a biologically active complex exhibiting antioxidant activity.

Cerium Oxide Nanoparticles: A New Therapeutic Tool in Liver Diseases

Oxidative stress induced by the overproduction of free radicals or reactive oxygen species (ROS) has been considered as a key pathogenic mechanism contributing to the initiation and progression of injury in liver diseases. Consequently, during the last few years antioxidant substances, such as superoxide dismutase (SOD), resveratrol, colchicine, eugenol, and vitamins E and C have received increasing interest as potential therapeutic agents in chronic liver diseases. These substances have demonstrated their efficacy in equilibrating hepatic ROS metabolism and thereby improving liver functionality. However, many of these agents have not successfully passed the scrutiny of clinical trials for the prevention and treatment of various diseases, mainly due to their unspecificity and consequent uncontrolled side effects, since a minimal level of ROS is needed for normal functioning. Recently, cerium oxide nanoparticles (CeO₂NPs) have emerged as a new powerful antioxidant agent with therapeutic properties in experimental liver disease. CeO₂NPs have been reported to act as a ROS and reactive nitrogen species (RNS) scavenger and to have multi-enzyme mimetic activity, including SOD activity (deprotionation of superoxide anion into oxygen and hydrogen peroxide), catalase activity (conversion of hydrogen peroxide into oxygen and water), and peroxidase activity (reducing hydrogen peroxide into hydroxyl radicals). Consequently, the beneficial effects of CeO₂NPs treatment have been reported in many different medical fields other than hepatology, including neurology, ophthalmology, cardiology, and oncology. Unlike other antioxidants, CeO₂NPs are only active at pathogenic levels of ROS, being inert and innocuous in healthy cells. In the current article, we review the potential of CeO₂NPs in several experimental models of liver disease and their safety as a therapeutic agent in humans as well.

Pulmonary Exposure to Copper Oxide Nanoparticles Leads to Neurotoxicity via Oxidative Damage and Mitochondrial Dysfunction

Copper oxide nanoparticles (CuONPs) are widely used in pharmaceutical, food, and textile industries. They have been shown to cause lung, liver, and kidney damage. However, whether an intratracheal instillation of CuONPs would affect the brain and its underlying mechanisms remain poorly studied. In this study, healthy C57BL/6J male mice were equally subdivided into control group, low-dose (30 μg/animal), medium-dose (50 μg/animal), and high-dose (100 μg/animal) CuONPs-treated groups. Mice were subjected to acute exposure of CuONPs via intratracheal instillation. Brain histopathology, inflammatory factors, oxidative stress markers, and mitochondrial function-related protein expression were determined. Our results demonstrated that CuONPs caused a dose-dependent brain damage in mice. Histopathological changes in the brain, elevation of inflammatory factors (Tnf, Il-6), and significant alterations in oxidative stress markers were also observed after treatment with CuONPs. Intriguingly, we did not observe infiltration of macrophage cell. Moreover, Tim23, TFAM, and MFN2 protein expression levels showed the decreasing trend after treatment with CuONPs. Taken together, these results indicate that pulmonary exposure to CuONPs induces pathological damage, inflammation, oxidative stress, and mitochondrial dysfunction in the cerebral cortex, suggesting that neurotoxicity caused by pulmonary exposure of CuONPs needs more attention from the public and relevant departments.

PAS kinase deficiency reduces aging effects in mice

Several signaling pathways may be affected during aging. All are regulated by nutrient levels leading to a decline in mitochondrial function and autophagy and to an increase in oxidative stress. PAS Domain Kinase (PASK) is a nutrient and bioenergetic sensor. We have previously found that PASK plays a role in the control of hepatic metabolic balance and mitochondrial homeostasis. To investigate PASK’s role in hepatic oxidative stress during aging, we analyzed the mitochondrial function, glucose tolerance, insulin resistance, and lipid-related parameters in aged PASK-deficient mice. Hepatic Pask mRNA decreased in step with aging, being undetectable in aged wild-type (WT) mice. Aged PASK-deficient mice recorded lower levels of ROS/RNS compared to aged WT. The regulators of mitochondrial biogenesis, PGC1a, SIRT1 and NRF2, decreased in aged WT, while aged PASK-deficient mice recorded a higher expression of NRF2, GCLm and HO1 proteins and CS activity under fasted conditions. Additionally, aged PASK-deficient mice recorded an overexpression of the longevity gene FoxO3a, and maintained elevated PCNA protein, suggesting that hepatic cell repair mechanisms might be functional. PASK-deficient mice have better insulin sensitivity and no glucose intolerance, as confirmed by a normal HOMA-IR index. PASK may be a good target for reducing damage during aging.

Efficacy of phytosomal curcumin among patients with non-alcoholic fatty liver disease

Scientists proposed that curcumin could be used for treatment of non-alcoholic fatty liver disease (NAFLD). In this article, we aimed to identify the effect of curcumin on NAFLD improvement. Fifty patients with NAFLD, were divided into two groups in this randomized, double-blind, and controlled clinical trial. Patients in the curcumin group received 250 mg/day of phytosomal curcumin, while those in the control group received 250 mg/day of placebo for duration of eight weeks. Anthropometric measurements and fasting blood samples were taken once at the baseline and once at the end of the study. Analysis was performed on 45 patients (curcumin group n = 22, placebo group n = 22). According to between groups analysis, curcumin significantly reduced the carboxymethyl lisine (CML) (148 ± 108 ng/mL vs 197 ± 101 ng/mL, P = 0.04), 8-hydroxy-2' -deoxyguanosine (8-OHdG) (46.9 ± 31.1 ng/mL vs 52.1 ± 43.1 ng/mL P = 0.03), liver enzymes (P < 0.001), weight (P < 0.001), waist circumference (P < 0.001), body fat percent (P < 0.01), and body mass index (BMI) (P < 0.01) in comparison with placebo. However, curcumin supplementation compared to placebo did not reduce soluble receptors for advanced glycation end products (sRAGE), hip circumference, waist/hip, and fat free mass by the end of the study. Our study indicated that phytosamal curcumin might be able to reduce the NAFLD progress by reducing the anthropometric measures, AGEs, and DNA damage. However, we need more studies with longer intervention duration, and larger sample size.

Pas Kinase Deficiency Triggers Antioxidant Mechanisms in the Liver

Metabolic dysfunction in the liver is the cause of numerous pathologies, which are associated with an altered redox state. PASK (PAS Domain Kinase) is a nutrient and bioenergetic sensor. We contend that PASK could act as an oxidative stress sensor in liver and/or control the metabolic balance, playing a role in the mitochondrial homeostasis. Using PASK-deficient mice, we observed that PASK deficiency promotes antioxidant response mechanisms: a lower production of ROS/RNS under non-fasting conditions, overexpression of genes coding to ROS-detoxifying enzymes and mitochondrial fusion proteins (MnSod Gpx, Mfn1 and Opa1), coactivator Ppargc1a, transcription factors (Pparg and FoxO3a) and deacetylase Sirt1. Also, under fasting conditions, PASK deficiency induced the overexpression of Ppargc1a, Ppara, Pparg, FoxO3a and Nrf2 leading to the overexpression of genes coding to antioxidant enzymes such as MnSOD, Cu/ZnSOD, GPx, HO1 and GCLm. Additionally, inducing PINK1 involved in cell survival and mitophagy. These changes kept ROS steady levels and improved the regenerative state. We suggest a new role for PASK as a controller of oxidative stress and mitochondrial dynamics in the liver. In fact, antioxidant response is PASK dependent. PASK-targeting could therefore be a good way of reducing the oxidative stress in order to prevent or treat liver diseases.

Immunomodulation by Processed Animal Feed: The Role of Maillard Reaction Products and Advanced Glycation End-Products (AGEs)

The immune system provides host protection to infection with pathogenic organisms, while at the same time providing tolerance upon exposure to harmless antigens. Thus, an impaired immune function is associated with increased susceptibility to infections with increased disease severity and thereby necessitating the therapeutic use of antibiotics. Livestock performance and feed efficiency, in addition to their health status, are dependent on the microbial load of their gut, the barrier function of the intestinal epithelium and the activity of the mucosal immune system, all of which can be modulated by dietary components. The majority of feeds that are consumed in pets and livestock have been processed. Processing promotes a non-enzymatic reaction between proteins and sugars called Maillard reaction (MR). Maillard reaction products (MRPs) and advanced Maillard reaction products (AGEs) determine taste, smell, and color of many food products therefore the MR is highly relevant for the feed industry. MRPs interact with different types of immune receptors, including the receptor for advanced glycation end products (RAGE) and immunomodulatory potential of feed proteins can be modified by Maillard reaction. This MR has become an important concern since MRPs/AGEs have been shown to contribute to increasing prevalence of diet-related chronic inflammatory states in the gut with negative health consequences and performance. The immunomodulatory effects of dietary MRPs and AGEs in livestock and pet animals are far less well-described, but widely considered to be similar to the relevant concepts and mechanisms obtained in the human field. This review will highlight immunological mechanisms underlying initiation of the innate and adaptive immune responses by MRPs/AGEs present in animal feeds, which are currently not completely understood. Bridging this knowledge gap, and taking advantage of progress in the human field, will significantly improve nutritional quality of feed and increase the prevention of diet-mediated inflammation in animals.

Tanshinol ameliorates CCl4-induced liver fibrosis in rats through the regulation of Nrf2/HO-1 and NF-κB/IκBα signaling pathway

Tanshinol, a water-soluble component isolated from Salvia miltiorrhiza Bunge, has a variety of biological activities involving anti-fibrotic effect. However, the exact role and the underlying mechanisms remain largely unclear. This study mainly focused on the anti-hepatic fibrotic activities and mechanisms of tanshinol on carbon tetrachloride (CCl4)-induced liver fibrosis in rats via anti-oxidative and anti-inflammation pathways. The rats were divided into 4 groups as follows: control, model, tanshinol 20 mg/kg, and tanshinol 40 mg/kg. Except for the control group, CCl4 was used to induce liver fibrosis processing for 8 weeks, meanwhile rats in tanshinol groups were intraperitoneally injected with additional tanshinol. Control group simultaneously received the same volumes of olive oil and saline. The potentially protective effect and mechanisms of tanshinol on liver fibrosis in rats were evaluated. The serum levels of alanine aminotransferase, aspartate aminotransferase, and total bilirubin were obviously lower in the tanshinol treatment groups related to model group. Compared with the model group, the levels of hyaluronic acid, type IV collagen, Laminin (LN), and procollagen III peptide (PIIIP) in serum were significantly decreased after tanshinol treatment. Furthermore, tanshinol could regulate Nrf2/HO-1 signaling pathway and increase the level of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), and also decrease the level of malondialdehyde (MDA) to against damage induced by oxidative stress. Simultaneously tanshinol could regulate nuclear factor kappa B signaling pathway to inhibit expression of inflammation factors, including transforming growth factor-β, tumor necrosis factor-α, Cox-2, interleukin-1β, and interleukin-6. In summary, our research demonstrated that tanshinol has protective effect on CCl4-induced liver fibrosis via inhibiting oxidative stress and inflammation, which may be associated with the regulation of nuclear factor erythroid2-related factor 2/hemeoxygenase-a and nuclear factor kappa B/inhibitor of kappa B alpha signaling pathways.

Static Magnetic Fields Modulate the Response of Different Oxidative Stress Markers in a Restraint Stress Model Animal

Stress is a state of vulnerable homeostasis that alters the physiological and behavioral responses. Stress induces oxidative damage in several organs including the brain, liver, kidney, stomach, and heart. Preliminary findings suggested that the magnetic stimulation could accelerate the healing processes and has been an effective complementary therapy in different pathologies. However, the mechanism of action of static magnetic fields (SMFs) is not well understood. In this study, we demonstrated the effects of static magnetic fields (0.8 mT) in a restraint stressed animal model, focusing on changes in different markers of oxidative damage. A significant increase in the plasma levels of nitric oxide (NO), malondialdehyde (MDA), and advanced oxidation protein products (AOPP), and a decrease in superoxide dismutase (SOD), glutathione (GSH), and glycation end products (AGEs) were observed in restraint stress model. Exposure to SMFs over 5 days (30, 60, and 240 min/day) caused a decrease in the NO, MDA, AGEs, and AOPP levels; in contrast, the SOD and GSH levels increased. The response to SMFs was time-dependent. Thus, we proposed that exposure to weak-intensity SMFs could offer a complementary therapy by attenuating oxidative stress. Our results provided a new perspective in health studies, particularly in the context of oxidative stress.

Relationship between advanced glycation end products and gestational diabetes mellitus

Objective: To investigate the levels of and dynamic changes of advanced glycation end products (AGEs) in maternal plasma during pregnancy and explore the association between these levels and gestational diabetes mellitus (GDM). Methods: This study recruited 90 GDM women and 90 healthy pregnant controls. The women received prenatal care and were hospitalized for delivery in Peking University First Hospital in China between October 2015 and April 2016. The patients were recruited and provided blood samples during gestational weeks 24-29. The levels of AGEs, TNF-α, hs-CRP, plasma glucose, and FINS and lipid profiles were measured, and HOMA-IR was calculated. New blood samples were collected and AGE was measured again in the two groups at 33-41 weeks of gestation to identify its dynamic changes. Results: The levels of AGEs were significantly higher in the GDM group than in the NGT group at both 24-29 weeks (473.65 ± 105.32 versus 324.36 ± 57.86 ng/L; p < .001) and 33-41 weeks (533.47 ± 146.95 versus 315.50 ± 77.79 ng/L; p < .001), and plasma levels of TNF-α and hs-CRP were significantly higher in the GDM group than in the NGT group (282.58 ± 45.85 versus 177.54 ± 35.14 pg/mL; 1.11 ± 0.25 versus 0.6 ± 0.19 µg/mL; p < .001), even after adjusting for other confounding factors, AGE levels were positively correlated with the levels of 2hPG (p = .003), TNF-α (p = .005), and hs-CRP (p < .001). A logistic regression analysis showed that AGE (OR = 1.037, 95%CI: 1.017 ∼ 1.058) and TNF-α (OR = 1.115, 95%CI: 1.048 ∼ 1.186) levels were independent risk factors for GDM. In the GDM group, the concentration of AGEs was significantly higher at 33-41 weeks than at 24-29 weeks (p = .001). In the NGT group, there was no significant change in the concentration of AGEs between the two gestational periods (p = .388). Conclusions: Plasma levels of AGEs are associated with GDM. During pregnancy, the changes observed in the levels of AGEs were different between GDM and normal pregnancies.

Do Coffee Polyphenols Have a Preventive Action on Metabolic Syndrome Associated Endothelial Dysfunctions? An Assessment of the Current Evidence

Epidemiologic studies from several countries have found that mortality rates associated with the metabolic syndrome are inversely associated with coffee consumption. Metabolic syndrome can lead to arteriosclerosis by endothelial dysfunction, and increases the risk for myocardial and cerebral infarction. Accordingly, it is important to understand the possible protective effects of coffee against components of the metabolic syndrome, including vascular endothelial function impairment, obesity and diabetes. Coffee contains many components, including caffeine, chlorogenic acid, diterpenes and trigonelline. Studies have found that coffee polyphenols, such as chlorogenic acids, have many health-promoting properties, such as antioxidant, anti-inflammatory, anti-cancer, anti-diabetes, and antihypertensive properties. Chlorogenic acids may exert protective effects against metabolic syndrome risk through their antioxidant properties, in particular toward vascular endothelial cells, in which nitric oxide production may be enhanced, by promoting endothelial nitric oxide synthase expression. These effects indicate that coffee components may support the maintenance of normal endothelial function and play an important role in the prevention of metabolic syndrome. However, results related to coffee consumption and the metabolic syndrome are heterogeneous among studies, and the mechanisms of its functions and corresponding molecular targets remain largely elusive. This review describes the results of studies exploring the putative effects of coffee components, especially in protecting vascular endothelial function and preventing metabolic syndrome.

Caffeic acid phenethyl ester up-regulates antioxidant levels in hepatic stellate cell line T6 via an Nrf2-mediated mitogen activated protein kinases pathway

AIM

To investigate the antioxidant effect of caffeic acid phenethyl ester (CAPE) in hepatic stellate cell-T6 (HSC-T6) cells cultured in vitro and the potential mechanisms.

METHODS

HSC-T6 cells were cultured in vitro and treated with various concentrations of CAPE for 24, 48 and 72 h, respectively. Cell proliferation was investigated using the MTT assay, and cell ultrastructural alterations were observed by transmission electron microscopy. Flow cytometry was employed to investigate the effects of CAPE on apoptosis and the levels of reactive oxygen species in HSC-T6 cells cultured in vitro. An enzyme immunoassay instrument was used to evaluate antioxidant enzyme expression. The effect on α-smooth muscle actin was shown using immunofluorescence. Gene and protein levels of Nrf2, related factors, and mitogen activated protein kinases (MAPKs), in HSC-T6 cells were detected using RT-PCR and Western blot, respectively.

RESULTS

CAPE inhibited the proliferation and activation of HSC-T6 cells cultured in vitro. CAPE increased the antioxidant levels and the translocation of Nrf2 from the cytoplasm to the nucleus in HSC-T6 cells. Moreover, the phosphorylation of MAPKs in cells decreased in response to CAPE. Interestingly, CAPE-induced oxidative stress in the cells was significantly attenuated by pretreatment with MAPKs inhibitors.

CONCLUSION

CAPE inhibits cell proliferation and up-regulates the antioxidant levels in HSC-T6 cells partly through the Nrf2-MAPKs signaling pathway.

Beneficial effects of Plantago albicans on high-fat diet-induced obesity in rats

Obesity is a one of the main global public health problems associated with chronic diseases such as coronary heart disease, diabetes and cancer. As a solution to obesity, we suggest Plantago albicans, which is a medicinal plant with several biological effects. This study assesses the possible anti-obesity protective properties of Plantago albicans in high fat diet-fed rats. 28 male Wistar rats were divided into 4 groups; a group which received normal diet (C), the second group was fed HDF diet (HDF), the third group was given normal diet supplemented with Plantago albicans (P.AL), and the fourth group received HDF supplemented with Plantago albicans (HDF+P.AL) (30mg/kg/day) for 7 weeks. Our results showed an increase in body weight of HDF rats by ∼16% as compared to the control group with an increase in the levels of total cholesterol (TC) as well as LDL-cholesterol, triglycerides (TG) in serum. Also, the concentration of TBARS increased in the liver and heart of HDF-fed rats as compared to the control group. The oral gavage of Plantago albicans extract to obese rats induced a reduction in their body weight, lipid accumulation in liver and heart tissue, compared to the high-fat diet control rats. The obtained results proved that the antioxidant potency of Plantago albicans extracts was correlated with their phenolic and flavonoid contents. The antioxidant capacity of the extract was evaluated by DPPH test (as EC50=250±2.12μg/mL) and FRAP tests (as EC50=27.77±0.14μg/mL). These results confirm the phytochemical and antioxidant impact of Plantago albicans extracts. Plantago albicans content was determined using validated HPLC methodology.

Role of renin-angiotensin system in liver diseases: an outline on the potential therapeutic points of intervention

The current review aimed to outline the functions of the renin angiotensin system (RAS) in the context of the oxidative stress-associated liver disease. Areas covered: Angiotensin II (Ang II) as the major effector peptide of the RAS is a pro-oxidant and fibrogenic cytokine. Mechanistically, NADPH oxidase (NOX) is a multicomponent enzyme complex that is able to generate reactive oxygen species (ROS) as a downstream signaling pathway of Ang II which is expressed in liver. Ang II has a detrimental role in the pathogenesis of chronic liver disease through possessing pro-oxidant, fibrogenic, and pro-inflammatory impact in the liver. The alternative axis (ACE2/Ang(1-7)/mas) of the RAS serves as an anti-inflammatory, antioxidant and anti-fibrotic component of the RAS. Expert commentary: In summary, the use of alternative axis inhibitors accompanying with ACE2/ Ang(1-7)/mas axis activation is a promising new strategy serving as a novel therapeutic option to prevent and treat chronic liver diseases.

Noninvasive mapping of the redox status of dimethylnitrosamine-induced hepatic fibrosis using in vivo dynamic nuclear polarization-magnetic resonance imaging

Hepatic fibrosis is a chronic disorder caused by viral infection and/or metabolic, genetic and cholestatic disorders. A noninvasive procedure that enables the detection of liver fibrosis based on redox status would be useful for disease identification and monitoring, and the development of treatments. However, an appropriate technique has not been reported. This study describes a novel method for assessing the redox status of the liver using in vivo dynamic nuclear polarization-magnetic resonance imaging (DNP-MRI) with the nitroxyl radical carbamoyl-PROXYL as a molecular imaging probe, which was tested in dimethylnitrosamine-treated mice as a model of liver fibrosis. Based on the pharmacokinetics of carbamoyl-PROXYL in control livers, reduction rate mapping was performed in fibrotic livers. Reduction rate maps demonstrated a clear difference between the redox status of control and fibrotic livers according to the expression of antioxidants. These findings indicate that in vivo DNP-MRI with a nitroxyl radical probe enables noninvasive detection of changes in liver redox status.

Ethanolic extract of Passiflora edulis Sims leaves inhibits protein glycation and restores the oxidative burst in diabetic rat macrophages after Candida albicans exposure

abstract This study was conducted to evaluate the effects of the ethanolic extract of Passiflora edulis leaves on blood glucose, protein glycation, NADPH oxidase activity and macrophage phagocytic capacity after Candida albicans exposure in diabetic rats. The Passiflora edulis Sims leaves were dried to 40°C, powdered, extracted by maceration in 70% ethanol, evaporated under reduced pressure and lyophilised. The biochemical tests performed were total phenolic content (TP) as determined by the Folin-Ciocalteu assay, trapping potential DPPH assay and total iron-reducing potential. Diabetes was induced by alloxan injection. Protein glycation was determined by AGE and fructosamine serum concentrations. Extract-treated diabetic animals demonstrated lower fructosamine concentrations compared with the diabetic group. Our results suggest that ethanolic Passiflora edulis Sims leaf extraction may have beneficial effects on diabetes and may improve glycaemic control in diabetic rats.

Mitochondria-related miR-141-3p contributes to mitochondrial dysfunction in HFD-induced obesity by inhibiting PTEN

Mitochondria-related microRNAs (miRNAs) have recently emerged as key regulators of cell metabolism and can modulate mitochondrial fusion and division. In order to investigate the roles of mitochondria-related miRNAs played in obesity, we conducted comprehensive molecular analysis in vitro and in vivo. Based on high-fat-diet (HFD) induced obese mice, we found that hepatic mitochondrial function was markedly altered. Subsequently, we evaluated the expression levels of selected mitochondria-related miRNAs and found that miR-141-3p was up-regulated strikingly in HFD mice. To further verify the role of miR-141-3p in obesity, we carried out gain-and-loss-of-function study in human HepG2 cells. We found that miR-141-3p could modulate ATP production and induce oxidative stress. Through luciferase report gene assay, we identified that phosphatase and tensin homolog (PTEN) was a target of miR-141-3p. Inhibiting PTEN could alter the mitochondrial function, too. Our study suggested that mitochondria-related miR-141-3p induced mitochondrial dysfunction by inhibiting PTEN.

Advanced glycation end-products: modifiable environmental factors profoundly mediate insulin resistance

Advanced glycation end-products are toxic by-products of metabolism and are also acquired from high-temperature processed foods. They promote oxidative damage to proteins, lipids and nucleotides. Aging and chronic diseases are strongly associated with markers for oxidative stress, especially advanced glycation end-products, and resistance to peripheral insulin-mediated glucose uptake. Modifiable environmental factors including high levels of refined and simple carbohydrate diets, hypercaloric diets and sedentary lifestyles drive endogenous formation of advanced glycation end-products via accumulation of highly reactive glycolysis intermediates and activation of the polyol/aldose reductase pathway producing high intracellular fructose. High advanced glycation end-products overwhelm innate defenses of enzymes and receptor-mediated endocytosis and promote cell damage via the pro-inflammatory and pro-oxidant receptor for advanced glycation end-products. Oxidative stress disturbs cell signal transduction, especially insulin-mediated metabolic responses. Here we review emerging evidence that restriction of dietary advanced glycation end-products significantly reduces total systemic load and insulin resistance in animals and humans in diabetes, polycystic ovary syndrome, healthy populations and dementia. Of clinical importance, this insulin sensitizing effect is independent of physical activity, caloric intake and adiposity level.

Methylmercury effects on migratory behaviour in glass eels (Anguilla anguilla): an experimental study using isotopic tracers

The effect of methylmercury (MeHg) on glass eels' propensity to migrate, mitochondrial activity and antioxidative defence systems was investigated. Marine glass eels were first sorted in an experimental flume according to their response to dusk. Fish responding to the decrease in light intensity by ascending in the water column and moving with or against the flow were considered as having a high propensity to migrate (migrant). Glass eels still sheltering at the end of the 24 h catching period were considered as having a low propensity to migrate and were called non-migrant. Migrant and non-migrant glass eels were then individually tagged and exposed to isotopically enriched (201)MeHg (50 ng L(-1)) for 11 days. The effect of contamination was studied on muscle fibre structure, and the expression level of genes involved in mitochondrial activity and antioxidative defence systems. To investigate the effect of MeHg on glass eel behaviour, migrant and non-migrant glass eels were sorted again and the bioaccumulation of (201)MeHg and its demethylation product ((201)Hg(II)) were determined for each individual. MeHg exposure increased activity in non-migrant glass eels but not migratory behaviour. Contamination affected mitochondrial structure and metabolism and suggests a higher oxidative stress and activation of antioxidative defence systems in non-migrant glass eels. Overall, our results suggest that exposure to MeHg might induce an increase in energy expenditure and a higher vulnerability to predation in non-migrant glass eels in the wild.

Oxidative stress as a crucial factor in liver diseases

Redox state constitutes an important background of numerous liver disorders. The redox state participates in the course of inflammatory, metabolic and proliferative liver diseases. Reactive oxygen species (ROS) are primarily produced in the mitochondria and in the endoplasmic reticulum of hepatocytes via the cytochrome P450 enzymes. Under the proper conditions, cells are equipped with special molecular strategies that control the level of oxidative stress and maintain a balance between oxidant and antioxidant particles. Oxidative stress represents an imbalance between oxidant and antioxidant agents. Hepatocytic proteins, lipids and DNA are among the cellular structures that are primarily affected by ROS and reactive nitrogen species. The process results in structural and functional abnormalities in the liver. Thus, the phenomenon of oxidative stress should be investigated for several reasons. First, it may explain the pathogenesis of various liver disorders. Moreover, monitoring oxidative markers among hepatocytes offers the potential to diagnose the degree of liver damage and ultimately to observe the response to pharmacological therapies. The present report focuses on the role of oxidative stress in selected liver diseases.

Modulation of oxidative stress by proanthocyanidin in H2O2-exposed human diploid fibroblast cells

Proanthocyanidin (a persimmon-peel extract) is known to have potent antioxidative effects, but its protective action specifically against cellular damage has not been fully explored. In this work, we investigated the protective property of proanthocyanidin against cellular oxidative stress with an experimental model, H2O2-exposed human diploid fibroblasts (HDFs). To investigate the proposed underlying beneficial actions of proanthocyanidin as to cellular injury induced by H2O2, several major biochemical parameters were determined, including estimation of total reactive species (RS) generation, antioxidant enzyme activities, reduced glutathione (GSH)/oxidized glulathione (GSSG) ratio, and mitochondrial membrane potential. The results indicate that proanthocyanidin reduced total RS generation while enhancing the activities of catalase and glutathione reductase and the GSH/GSSG ratio. Additionally, proanthocyanidin was found to protect against mitochondrial membrane damage in HDFs treated H2O2. Based on these results, we conclude that proanthocyanidin has strong protective effects against cellular damage to several key cellular functions by suppressing oxidative stress in H2O2-treated HDFs.

Development of nonalcoholic hepatopathy: contributions of oxidative stress and advanced glycation end products. Int J Mol Sci. 2013;14:19846-19866. [PMID: 24084729 PMCID: PMC3821590 DOI: 10.3390/ijms141019846]

Advanced glycation end products (AGEs) are generated spontaneously in cells; however, under conditions of hyperglycemia and lipid peroxidation, their levels are higher than usual, which contribute to the development of diseases such as the nonalcoholic fatty liver disease (NAFLD). NAFLD is associated with oxidative stress (OS), which is linked to the transition of steatosis to steatohepatitis due to lipid peroxidation. The AGE-receptor interaction in hepatic stellate cells leads to an increase in reactive oxygen species and enhances the proliferation and activation of these cells, worsening liver fibrosis and disease progression. In this vicious cycle, there is production of (carboxymethyl)lysine, a biomarker for products of advanced glycation and lipid peroxidation, being a shared component between the two pathways. In this review, we aim to compile evidence to support the basic molecular mechanisms of AGEs and OS generation and their influence, independently or combined, on the evolution of NAFLD. The deeper understanding of the interrelations of AGEs + OS may help to elucidate the pathogenic pathways of NAFLD and to devise rational therapeutic interventions for this disease, with an expected positive impact on quality of life of patients.

High glucose enhances HIV entry into T cells through upregulation of CXCR4

It is well known that patients with HIV are prone to diabetes mellitus because of the side effects of HARRT. However, whether high glucose affects the HIV infection of T cells is not clear. Recent studies have shown that upregulation of GLUT-1 renders T cells susceptible to HIV infection. We hypothesized that hyperglycemia has the potential to increase HIV infection by enhancing its entry into immune cells. The effect of high glucose on HIV entry into T cells (Jurkat cells and PBMCs) and the mechanisms involved were investigated. High glucose significantly enhanced HIV entry, which was associated with increased T-cell expression of CXCR4. However, T cells with silenced HIF-1α displayed attenuated expression of CXCR4, whereas T cells with silenced CXCR4 showed decreased HIV entry in a high-glucose milieu. On the one hand, high glucose stimulated T-cell ROS generation, and H(2)O(2) at low concentrations enhanced the entry of HIV into T cells. On the other hand, inhibition of ROS not only attenuated high-glucose-mediated T-cell expression of CXCR4 and HIF-1α but also mitigated T-cell HIV entry in a high-glucose milieu. In our study, high glucose enhanced HIV entry into T cells by increasing expression of CXCR4 and HIF-1α.

TLR-4 signalling accelerates colon cancer cell adhesion via NF-κB mediated transcriptional up-regulation of Nox-1

Surgery induced inflammation is a potent promoter of tumour recurrence and metastasis in colorectal cancer. The recently discovered family of Nox enzymes represent a major source of endogenous reactive oxygen species (ROS) and are now heavily implicated in tumour cell metastasis. Interestingly, Nox enzymes can be ‘purposefully’ activated by inflammatory cytokines and growth factors which are present in abundance in the peri-operative window. As colon cancer cells express Nox enzymes and Toll-like receptor 4 (TLR-4), we hypothesised that LPS may potentiate the ability of colon cancer cells to metastasise via Nox enzyme mediated redox signalling. In support of this hypothesis, this paper demonstrates that LPS induces a significant, transient increase of endogenous ROS in SW480, SW620 and CT-26 colon cancer cells. This increase in LPS-induced ROS activity is completely abrogated by a Nox inhibitor, diphenyleneiodonium (DPI), Nox1 siRNA and an NF-κB inhibitor, Dihydrochloride. A significant increase in Nox1 and Nox2 protein expression occurs following LPS treatment. Inhibition of NF-κB also attenuates the increase of Nox1 and Nox2 protein expression. The sub-cellular location of LPS-induced ROS generation lies mainly in the endoplasmic reticulum. LPS activates the PI3K/Akt pathway via Nox generated ROS and this signal is inhibited by DPI. This LPS activated Nox mechanism facilitates a significant increase in SW480 colon cancer cell adhesion to collagen I, which is inhibited by DPI, Nox1 siRNA and a PI3K inhibitor. Altogether, these data suggest that the LPS-Nox1 redox signalling axis plays a crucial role in facilitation of colon cancer cell adhesion, thus increasing the metastatic potential of colon cancer cells. Nox1 may represent a valuable target in which to prevent colon cancer metastasis.

Melatonin: the smart killer: the human trophoblast as a model

Melatonin has both the ability to induce intrinsic apoptosis in tumor cells while it inhibits it in non-tumor cells. Melatonin kills tumor cells through induction of reactive oxygen species generation and activation of pro-apoptotic pathways. In contrast, melatonin promotes the survival of non-tumor cells due to its antioxidant properties and the inhibition of pro-apoptotic pathways. In primary human villous trophoblast, a known pseudo-tumorigenic tissue, melatonin promotes the survival through inhibition of the Bax/Bcl-2 pathway while in BeWo choriocarcinoma cell line melatonin induces permeabilization of the mitochondrial membrane leading to cellular death. These findings suggest that the trophoblast is a good model to study the differential effects of melatonin on the intrinsic apoptosis pathway. This review describes the differential effects of melatonin on the intrinsic apoptosis pathway in tumor and non-tumor cells and presents the trophoblast as a novel model system in which to study these effects of melatonin.

Strategies to target mitochondria and oxidative stress by antioxidants: key points and perspectives

For several decades, many antioxidants studies have emphasized the marked disparity between the beneficial effect of the antioxidants shown in preclinical studies and their inability to show beneficial effects in clinical trials. Besides, it is not uncommon to find highly contradictory clinical results, which may explain why consumers are less enthusiastic for antioxidant uses. This perspective article aims to highlights the critical role of Reactive Oxygen Species (ROS) and antioxidants, the potential mechanisms that might account for these discrepancies in clinical trials and some strategies to target oxidative stress and mitochondria by antioxidants. We need urgently to set up standard methods to evaluate antioxidants and oxidative stress in human and in particular at mitochondria level. The determination of what the basal level of ROS is in normal human may be used to identify pathologic ROS levels in patients and ultimately guide antioxidants treatment.

D-galactose effectiveness in modeling aging and therapeutic antioxidant treatment in mice

Accumulating evidence suggests that mitochondrial dysfunction and oxidative stress play major roles in aging. Chronic administration of D-galactose has been reported to cause deterioration of cognitive and motor skills that are similar to symptoms of aging and, therefore, is regarded as a model of accelerated aging. Because enhancing endogenous antioxidants is now widely regarded as an attractive therapy for conditions associated with mitochondrial oxidative stress, in the present study the effects of α-lipoic acid, L-carnitine, and PMX-500F on D-galactose treated mice were tested. Female mice were injected with (100 mg/kg) D-(+)-galactose for 6 weeks and some groups were treated with a daily dose of α-lipoic acid (5 mg/kg), L-carnitine (3.9 mg/kg), PMX-500F (11.9 mg/kg), or the vehicle (0.1 M Tris, pH 7.4). Control mice were treated with physiological saline. An accelerating Rota-Rod, open field test, and Y-maze test were performed, and serum lactate concentrations were analyzed. These analyses did not identify impairment in motor coordination, open-field activity, or spatial memory (p > 0.05). Similarly, serum lactate concentrations in D-galactose-treated mice were not elevated when compared to controls (p > 0.05). Treatment with the antioxidant compounds at the given concentrations did not result in any changes in the behavioral parameters tested. In conclusion, results of this study illustrate that chronic, short-term D-galactose treatment may not represent a suitable model for inducing readily detectable age-related neurobehavioral symptoms in mice.