Comparative cytoprotective activity of vitamin C, E and beta-carotene against chromium induced oxidative stress in murine macrophages

Environmental Chemical-Induced Reactive Oxygen Species Generation and Immunotoxicity: A Comprehensive Review

Significance: Reactive oxygen species (ROS), the reactive oxygen-carrying chemicals moieties, act as pleiotropic signal transducers to maintain various biological processes/functions, including immune response. Increased ROS production leads to oxidative stress, which is implicated in xenobiotic-induced adverse effects. Understanding the immunoregulatory mechanisms and immunotoxicity is of interest to developing therapeutics against xenobiotic insults. Recent Advances: While developmental studies have established the essential roles of ROS in the establishment and proper functioning of the immune system, toxicological studies have demonstrated high ROS generation as one of the potential mechanisms of immunotoxicity induced by environmental chemicals, including heavy metals, pesticides, aromatic hydrocarbons (benzene and derivatives), plastics, and nanoparticles. Mitochondrial electron transport and various signaling components, including NADH oxidase, toll-like receptors (TLRs), NF-κB, JNK, NRF2, p53, and STAT3, are involved in xenobiotic-induced ROS generation and immunotoxicity. Critical Issues: With many studies demonstrating the role of ROS and oxidative stress in xenobiotic-induced immunotoxicity, rigorous and orthogonal approaches are needed to achieve in-depth and precise understanding. The association of xenobiotic-induced immunotoxicity with disease susceptibility and progression needs more data acquisition. Furthermore, the general methodology needs to be possibly replaced with high-throughput precise techniques. Future Directions: The progression of xenobiotic-induced immunotoxicity into disease manifestation is not well documented. Immunotoxicological studies about the combination of xenobiotics, age-related sensitivity, and their involvement in human disease incidence and pathogenesis are warranted. Antioxid. Redox Signal. 40, 691-714.

Detoxification effects of ascorbic acid on the oxidative stress, neurotoxicity, and metallothionein (MT) gene expression in juvenile rockfish, Sebastes schlegelii by the dietary chromium exposure

Juvenile rockfish Sebastes schlegelii (mean length 10.8 ± 1.4 cm, and mean weight 31.7 ± 3.6 g) were exposed for 4 weeks with the different levels of dietary chromium (Cr⁶⁺) at 0, 120 and 240 mg/L and ascorbic acids (AsA) at 100, 200 and 400 mg/L. Superoxide dismutase (SOD) activity, glutathione S-transferase (GST) activity, and glutathione (GSH) level of liver and gill were evaluated as antioxidant response indicators for the 4 weeks exposure. The SOD and GST activity of liver and gill were substantially increased by the high concentrations of dietary Cr exposure, whereas a significant decrease was observed in the GSH levels of liver and gill. Metallothionein (MT) gene in liver was significant stimulated in the response to the dietary Cr exposure. In neurotoxicity, AChE activity was considerably inhibited in brain and muscle tissues by dietary Cr exposure. The high levels of AsA supplementation were highly effective to attenuate the alterations in the antioxidant responses, MT gene expression, and AChE activity by the dietary Cr exposure.

Molecular Mechanisms and Pathways as Targets for Cancer Prevention and Progression with Dietary Compounds

A unique feature of bioactive food ingredients is their broad antioxidant function. Antioxidants having a wide spectrum of chemical structure and activity beyond basic nutrition; display different health benefits by the prevention and progression of chronic diseases. Functional food components are capable of enhancing the natural antioxidant defense system by scavenging reactive oxygen and nitrogen species, protecting and repairing DNA damage, as well as modulating the signal transduction pathways and gene expression. Major pathways affected by bioactive food ingredients include the pro-inflammatory pathways regulated by nuclear factor kappa B (NF-κB), as well as those associated with cytokines and chemokines. The present review summarizes the importance of plant bioactives and their roles in the regulation of inflammatory pathways. Bioactives influence several physiological processes such as gene expression, cell cycle regulation, cell proliferation, cell migration, etc., resulting in cancer prevention. Cancer initiation is associated with changes in metabolic pathways such as glucose metabolism, and the effect of bioactives in normalizing this process has been provided. Initiation and progression of inflammatory bowel diseases (IBD) which increase the chances of developing of colorectal cancers can be downregulated by plant bioactives. Several aspects of the potential roles of microRNAs and epigenetic modifications in the development of cancers have also been presented.

Short communication: effect of saccharomyces cerevisiae supplementation on some biomarkers of oxidative stress in weaned rabbits during the hot-dry season

<p>A feeding trial was conducted to evaluate the effect of Saccharomyces cerevisiae (SC) supplementation on some biomarkers of oxidative stress in rabbits during the hot-dry season (temperaturehumidity index: 33.2±0.9oC). Sixty healthy weaned crossbred rabbits, aged between 5-6 wk with live weight of 612.7±60.8 g (mean±standard deviation) were used. The rabbits were divided into 5 treatment groups; SC0 receiving a control diet without supplementation of SC, and SC2, SC4, SC6 and SC8 receiving the control diet supplemented with SC at the rate of 2, 4, 6 and 8×109 colony forming units/kg, respectively. The activity of total superoxide dismutase and malonaldehyde in serum were not significantly affected, but serum catalase concentration rose (P&lt;0.05) as the SC inclusion level increased. Although further studies are required, baker’s yeast containing SC could help ameliorate the adverse effects of heat stress in rabbits.</p><p> </p>

4-chloro-1,2-phenylenediamine induces apoptosis in Mardin-Darby canine kidney cells via activation of caspases

4-Chloro-1,2-phenylenediamine (4-Cl-o-PD) is a halogenated aromatic diamine that was used as a precursor for manufacturing permanent hair dyes. Despite its well-documented mutagenic and carcinogenic effects in a number of in vitro and in vivo models, its cytotoxicity and mode of action have not received similar attention. Here, we investigated the effect of 4-Cl-o-PD on Mardin-Darby canine kidney cells. It induced apoptosis and the evidence suggests its initiation by reactive oxygen species (ROS). The results of various assays used show a dose-dependent (i) decrease in cell viability, (ii) increase in cells at sub-G1 phase and the G0/G1 phase arrested in cell cycle, (iii) increase in intracellular ROS accompanied by depletion of glutathione, and (iv) that apoptotic cell death probably involves activation of both intrinsic and extrinsic pathways.

Anti-oxidative and anti-genotoxic effects of methanolic extract of Mentha pulegium on human lymphocyte culture

In the present work, methanolic extract of Mentha pulegium from Erzurum, Turkey, was used in order to report the results of anti-oxidant capacity, anti-oxidant activity and anti-genotoxic effects. The total antioxidant capacity and total phenolic content were measured by using CUPRAC, ABTS and Folin-Ciocalteu colorimetric methods. The total phenolic content was higher than the total antioxidant capacity (for the results of both the CUPRAC and ABTS methods) of methanolic extract of M pulegium (ME). Also, we evaluated the anti-oxidant enzyme activity such as superoxide dismutase (SOD) and glutation peroxidase, total glutation (GSH) and malondialdehyde (MDA) in human lymphocyte culture. In CCl₄-treated group, the activity of SOD, glutathione peroxidase (GPx) and GSH decreased significantly and the level of MDA increased significantly. A significant increase in the activity of SOD, GPx and the level of GSH were seen when supplemented with ME to CCl₄-treated group. Furthermore, a significant decrease in the level of MDA was observed when compared with CCl₄ alone treated group. In addition, anti-genotoxic effect of ME was studied by using sister chromatid exchange (SCE) method. As a result, ME has shown anti-genotoxic effect depend on anti-oxidative effect on human lymphocyte culture.

Anti-oxidative and anti-genotoxic effects of carnosine on human lymphocyte culture

The aim of this study was to investigate the effects of carnosine, a biological antioxidant, on the oxidative stress and genotoxicity by a single dose of carbon tetrachloride (CCl4; 5 mM) in the human lymphocyte culture. We studied the anti-genotoxic effects of carnosine by using sister chromatid exchange (SCE) test system. Also, the anti-oxidative effects of carnosine were evaluated by using superoxide dismutase (SOD), glutathione peroxidase (GPx), total glutathione (GSH) and malondialdehyde (MDA) assay. The SCE frequency was increased when treated with CCl4. Carnosine at 10 and 20 mM reduced SCE frequency in the human lymphocyte ( p < 0.001). In addition, CCl4 treatment significantly depleted the level of GSH, reduced the activity of SOD and GPx and elevated the level of MDA ( p < 0.001). Carnosine treatment led to significant attenuation of CCl4-induced oxidative stress by normalization of the activities of SOD and GPx and the level of GSH and MDA ( p < 0.05 or 0.001). These results suggest that carnosine could provide anti-oxidative and anti-genotoxic protection for the oxidative and genotoxic agents that cause many diseases including cancer and neurodegenerative disease.

Selective macrophage ascorbate deficiency suppresses early atherosclerosis

To test whether severe ascorbic acid deficiency in macrophages affects progression of early atherosclerosis, we used fetal liver cell transplantation to generate atherosclerosis-prone apolipoprotein E-deficient (apoE(-/-)) mice that selectively lacked the ascorbate transporter (SVCT2) in hematopoietic cells, including macrophages. After 13 weeks of chow diet, apoE(-/-) mice lacking the SVCT2 in macrophages had surprisingly less aortic atherosclerosis, decreased lesion macrophage numbers, and increased macrophage apoptosis compared to control-transplanted mice. Serum lipid levels were similar in both groups. Peritoneal macrophages lacking the SVCT2 had undetectable ascorbate; increased susceptibility to H(2)O(2)-induced mitochondrial dysfunction and apoptosis; decreased expression of genes for COX-2, IL1β, and IL6; and decreased lipopolysaccharide-stimulated NF-κB and antiapoptotic gene expression. These changes were associated with decreased expression of both the receptor for advanced glycation end products and HIF-1α, either or both of which could have been the proximal cause of decreased macrophage activation and apoptosis in ascorbate-deficient macrophages.

Suppression of oxidative stress and pro-inflammatory mediators by Cymbopogon citratus D. Stapf extract in lipopolysaccharide stimulated murine alveolar macrophages

Exploration of antioxidants of plant origin and their scientific validation for their immense pharmacological potential is emerging as an issue of intense research now-a-days.The effect of Cymbopogon citratus extract was seen on cell viability, oxidative stress markers i.e. ROS production, SOD activity, lipid peroxidation and GSH content of murine alveolar macrophages stressed with lipopolysaccharide. Modulation in release of NO and pro-inflammatory cytokine TNF-α along with alterations in mitochondrial membrane potential under stress were compared with known plant derived antioxidant quercetin. The extract was not found to be cytotoxic at any of the selected doses. At 5 and 10 μg the extract showed significant increase in SOD activity, GSH content (p<0.001), decrease in ROS production as seen by fluorescent dye DCFH-DA and also MDA formation (lipid peroxidation marker) significantly. The extract also showed reduction in the release of pro-inflammatory mediators TNF-α and NO significantly indicating an anti-inflammatory effect. The extract was able to restore mitochondrial membrane potential as estimated by spectrofluorimetry using the fluorescent dye Rhodamine 123. The results suggest potential use of the cytoprotective, antioxidant and anti-inflammatory property of C. citratus in the form of dietary component and also in formulations against lung inflammatory diseases where oxidative stress plays an important role.

Release of chromium from orthopaedic arthroplasties

Many orthopaedic implants are composed of alloys containing chromium. Of particular relevance is the increasing number of Cobalt Chromium bearing arthroplasies being inserted into young patients with osteoarthritis. Such implants will release chromium ions. These patients will be exposed to the released chromium for over 50 years in some cases. The subsequent chromium ion metabolism and redistribution in fluid and tissue compartments is complex. In addition, the potential biological effects of chromium are also controversial, including DNA and chromosomal damage, reduction in CD8 lymphocyte levels and possible hypersensitivity reactions (ALVAL). The establishment of these issues and the measurement of chromium in biological fluids is the subject of this review.

Oxidative stress as a component of chromium-induced cytotoxicity in rat calvarial osteoblasts

It has been documented that medical prosthetic alloys release metal ions into surrounding tissues and cause cytotoxicity, but the mechanisms remain undefined. In that regard the cellular oxidative stress may be a common pathway in cellular responses to metal ions. The objective of this study was to approach the hypothesis that oxidative stress mediates chromium-induced cytotoxicity in rat calvarial osteoblasts. Osteoblasts were exposed to different concentrations of Cr6+ or Cr3+ (5-20 microM) in the presence or absence of the antioxidant N-acetyl-cysteine (NAC; 1-5 mM). Cellular viability, differentiation, and intracellular ultrastructural alterations were evaluated by MTT assay, alkaline phosphatase (ALP) activity assay, and transmission electron microscopy. Cellular oxidative stress was evaluated by intracellular reactive oxygen species (ROS) production. ROS production was monitored by the oxidation-sensitive fluorescent probe 2'7'-dichlorofluorescin diacetate (DCFH-DA). A time- and concentration- dependent increased cytotoxicity, time-dependent increased intracellular ROS production were indicated on exposure to Cr6+. Pretreatment of osteoblasts with 1-5 mM NAC afforded dose-dependent cytoprotective effects against Cr6+-induced cytotoxicity in osteoblasts. NAC decreased the level of intracellular ROS induced by Cr6+, too. While Cr3+ and NAC did not have any significant effects on osteoblasts (5-20 microM). These results suggest that oxidative stress is involved in Cr6+-induced cytotoxicity in osteoblasts, and NAC can provide protection for osteoblasts against Cr6+-induced oxidative stress. Cr3+ (5-20 microM) have no significant cytotoxicity in osteoblasts based on the results of this study.

The interaction of chromium (VI) with macrophages: Depletion of glutathione and inhibition of glutathione reductase

There are reports of alterations in the number and functions of the cells of the immune system in patients with metal-on-metal (MOM) orthopaedic implants. These effects have been correlated with elevated chromium levels in the patients' blood. We have investigated the interactions of clinically relevant concentrations of Cr VI with macrophages in vitro, and the mechanisms responsible for its toxicity. Cr VI causes a concentration dependent decrease in macrophage viability above 1 microM as measured by the MTT and Neutral Red assays. This falls well within the range of circulating chromium serum concentrations measured in patients with MOM. Intracellular reduced glutathione (GSH) levels fall as a result, and most of the loss (86%) is accounted for by oxidation to the dimer, GSSG. Prior depletion of GSH does not sensitise the cells to Cr VI toxicity, implying that it is not involved in protecting the cells against the effects of Cr VI. During the metabolism of Cr VI, glutathione reductase activity is inhibited. In contrast, the activities of catalase and superoxide dismutase are not significantly altered. Prior inhibition of glutathione reductase activity protects against the toxicity of Cr VI to a significant extent, suggesting that it reduces Cr VI to a toxic metabolite.

Towards the development of a simplified long-term organ culture method for human scalp skin and its appendages under serum-free conditions

Organ culture of human scalp skin is usually performed with serum-containing medium, which limits its analytical usefulness. Here we report that intact human scalp skin can be grown at the air/liquid interface in supplemented, serum-free William's E medium for more than 2 weeks. Active hair shaft growth was visible until day 16 and was significantly enhanced compared with minimum essential medium (MEM) + 10% fetal bovine serum (FBS). Moreover, William's E medium protected better against cell death than MEM + 10% FBS before day 12. Using quantitative immunochemistry, proliferating (Ki-67+) cells could still be observed in the epithelium of hair follicles even on day 17 of serum-free skin organ culture. The number of apoptotic (TUNEL+) cells in the skin epithelium rose steadily after day 5. Giemsa stains revealed mature skin mast cells even after 13 days in culture. The percentage of surviving hair follicles (mostly with catagen- or telogen-like morphology) gradually increased over time displaying mostly catagen hair follicles after 17 days of culture. Although epidermis and hair follicle epithelium showed increasing atrophy and degeneration, and their pigmentation decreased gradually over time, some long-term-surviving epithelial islands were found in association with remnants of follicular structures as late as on day 88. These preliminary data suggest that a very simple serum-free organ culture method allows prolonged human skin and hair follicle survival as well as some limited hair follicle cycling in intact skin for more than 2 weeks under well-defined experimental conditions. This pragmatic assay invites multiple uses, and may become a valuable tool for both skin and hair research.