Roles of ROS mediated oxidative stress and DNA damage in 3-methyl-2-quinoxalin benzenevinylketo-1, 4-dioxide-induced immunotoxicity of Sprague–Dawley rats

Advances in Metabolism and Metabolic Toxicology of Quinoxaline 1,4-Di-N-oxides

Quinoxaline 1,4-di-N-Oxides (QdNOs) have been used as synthetic antimicrobial agents in animal husbandry and aquaculture. The metabolism and potential toxicity have been also concerns in recently years. The metabolism investigations showed that there were 8 metabolites of Carbadox (CBX), 34 metabolites of Cyadox (CYA), 33 metabolites of Mequindox (MEQ), 35 metabolites of Olaquindox (OLA), and 56 metabolites of Quinocetone (QCT) in different animals. Among them, Cb3 and Cb8, M6, and O9 are metabolic residual markers of CBX, MEQ and OLA, which are associated with N → O reduction. Toxicity studies revealed that QdNOs exhibited severe tumorigenicity, cytotoxicity, and adrenal toxicity. Metabolic toxicology showed that toxicity of QdNOs metabolites might be related to the N → O group reduction, and some metabolites exhibited higher toxic effects than the precursor, which could provide guidance for further research on the metabolic toxicology of QdNOs and provide a wealth of information for food safety evaluation.

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.

Evaluation of triazophos induced immunotoxicity of spleen and head kidney in fresh water teleost, Channa punctata

The utilization of pesticides has increased for destroying pests and protecting crops in the agriculture field. Triazophos is a commonly used organophosphorous insecticide that causes alterations in haematological and histological parameters in fish. The present study was designed to evaluate the effect of triazophos induced innate and cell mediated immunotoxicity in freshwater teleost, Channa punctata. Fishes were exposed to triazophos at concentrations 5 and 10% of LC₅₀ value for 10 and 20 days. Splenic and head kidney macrophage phagocytosis, nitric oxide production and superoxide production were assayed to evaluate the innate immunity. Cell-mediated immunity was measured through splenic and head kidney lymphocyte proliferation in presence of T and B cell mitogens. Results of the present study revealed that macrophage phagocytosis was significantly reduced after in vivo triazophos treatment. Differential suppressive effect of triazophos was also observed where mitogen induced splenic and head kidney lymphocyte proliferations were reduced after 10 and 20 days treatment. Concentration dependent effect of triazophos was observed in in vivo studies where the production of reactive oxygen and nitrogen intermediates were suppressed. This study describes the first investigation of the effect of triazophos on immune functions and will help to determine appropriate ecotoxicity and immunotoxicity in freshwater teleosts.

Mycobacterium smegmatis msmeg_3314 is involved in pyrazinamide and fluoroquinolones susceptibility via NAD+/NADH dysregulation

Aim: To identify and characterize new mycobacterium pyrazinamide (PZA) resistance genes in addition to pncA, rpsA and panD. Materials & methods: To screen a Tn7 M. smegmatis mc²155 transposon library using 50 μM PZA and a PZA hypersensitive mutant (M492) was obtained. MIC was further used to confirm the hypersensitivity of M492 mutant by culturing the mutant in Middlebrook 7H9 liquid medium at 37°C. Results: msmeg_3314 is the gene underlying the hypersensitive phenotype of mutant M492. The observed resistance to PZA and fluoroquinolones involved the alteration of Mycobacterium cell wall permeability and the dissipation of the proton motive force. NAD⁺/NADH dysregulation and attenuated glyoxylate shunt might underlie the declined scavenging capacity of reactive oxygen species in the msmeg_3314-deficient mutants. Conclusion: msmeg_ 3314 is a novel gene involved in pyrazinamide resistance and might be a new candidate for drugs target.

Inhibition of gap junction composed of Cx43 prevents against acute kidney injury following liver transplantation

Postoperative acute kidney injury (AKI) is a severe complication after liver transplantation (LT). Its deterioration and magnification lead to the increase in mortality. Connexin43 (Cx43) mediates direct transmission of intracellular signals between neighboring cells, always considered to be the potent biological basis of organ damage deterioration and magnification. Thus, we explored the effects of Cx43 on AKI following LT and its related possible mechanism. In this study, alternations of Cx43 expression were observed in 82 patients, receiving the first-time orthotopic LT. We built autologous orthotopic liver transplantation (AOLT) models with Sprague–Dawley (SD) rats in vivo, and hypoxia-reoxygenation (H/R) or lipopolysaccharide (LPS) pretreatment models with kidney tubular epithelial cells (NRK-52E) in vitro, both of which were the most important independent risk factors of AKI following LT. Then, different methods were used to alter the function of Cx43 channels to determine its protective effects on AKI. The results indicated that patients with AKI suffering from longer time of tracheal intubation or intensive care unit stay, importantly, had significantly lower survival rate at postoperative 30 days and 3 years. In rat AOLT models, as Cx43 was inhibited with heptanol, postoperative AKI was attenuated significantly. In vitro experiments, downregulation of Cx43 with selective inhibitors, or siRNA protected against post-hypoxic NRK-52E cell injuries caused by H/R and/or LPS, while upregulation of Cx43 exacerbated the above-mentioned cell injuries. Of note, alternation of Cx43 function regulated the content of reactive oxygen species (ROS), which not only mediated oxidative stress and inflammation reactions effectively, but also regulated necroptosis. Therefore, we concluded that Cx43 inhibition protected against AKI following LT through attenuating ROS transmission between the neighboring cells. ROS alternation depressed oxidative stress and inflammation reaction, which ultimately reduced necroptosis. This might offer new insights for targeted intervention for organ protection in LT, or even in other major surgeries.

Quinoxaline-1,4-dioxide derivatives inhibitory action in melanoma and brain tumor cells

Aim: Quinoxaline-1,4-dioxide derivatives are synthetic heterocyclic compounds with multiple biological and pharmacological effects. In this study, we investigated the bioactivity of five quinoxaline-1,4-di-N-oxides derivatives in different animal cell lines. Materials & methods: Using in vitro cell cultures, we evaluated the influence of quinoxaline-1,4-dioxide, 2-methylquinoxaline-1,4-dioxide, 2-amino-3-cyanoquinoxaline-1,4-dioxide, 3-methyl-2-quinoxalinecarboxamide-1,4-dioxide and 2-hydroxyphenazine-N,N-dioxide (2HF) in the viability, migration and proliferation of nonmalignant (3T3-L1 and human dermal microvascular endothelial cell) and malignant (B16-F10, MeWo, GL-261 and BC3H1) cell lines. Results: The viability IC₅₀ concentrations for each quinoxaline-1,4-di-N-oxide derivative were calculated, and a concomitant reduction of migration and proliferation was observed mainly in malignant cell lines. Conclusion: 2HF exhibited potent anti-viability, anti-migration and anti-proliferative actions selectively in tumor cells, nevertheless more studies are required to further investigate 2HF promising biologic effects.

Developmental toxicity, oxidative stress and immunotoxicity induced by three strobilurins (pyraclostrobin, trifloxystrobin and picoxystrobin) in zebrafish embryos

Strobilurins is the most widely used class of fungicides, but is reported highly toxic to some aquatic organisms. In this study, zebrafish embryos were exposed to a range concentrations of three strobilurins (pyraclostrobin, trifloxystrobin and picoxystrobin) for 96 h post-fertilization (hpf) to assess their aquatic toxicity. The 96-h LC₅₀ values of pyraclostrobin, trifloxystrobin and picoxystrobin to embryos were 61, 55, 86 μg/L, respectively. A series of symptoms were observed in developmental embryos during acute exposure, including decreased heartbeat, hatching inhibition, growth regression, and morphological deformities. Moreover, the three fungicides induced oxidative stress in embryos through increasing reactive oxygen species (ROS) and malonaldehyde (MDA) contents, inhibiting superoxide dismutase (SOD) activity and glutathione (GSH) content as well as differently changing catalase (CAT) activity and mRNA levels of genes related to antioxidant system (Mn-sod, Cu/Zn-sod, Cat, Nrf2, Ucp2 and Bcl2). In addition, exposure to the three strobilurins resulted in significant upregulation of IFN and CC-chem as well as differently changed expressions of TNFa, IL-1b, C1C and IL-8, which related to the innate immune system, suggesting that these fungicides caused immunotoxicity during zebrafish embryo development. The different response of enzymes and genes in embryos exposed to the three fungicides might be the cause that leads to the difference of their toxicity. This work made a comparison of the toxicity of three strobilurins to zebrafish embryos on multi-levels and would provide a better understanding of the toxic effects of strobilurins on aquatic organisms.

Developmental toxicity and potential mechanisms of pyraoxystrobin to zebrafish (Danio rerio)

As a newly developed, highly efficient strobilurin fungicide, pyraoxystrobin has been reported to be highly toxic to some aquatic organisms. However, the toxicity of pyraoxystrobin to different life stages of fish and the potential underlying mechanisms are still unknown. Hence, in the present study, the acute toxicity of pyraoxystrobin to different life stages of zebrafish (embryo, larva, and adult) was assessed. The developmental toxicity of pyraoxystrobin to zebrafish embryos and its effects on gene transcription in the embryo were also investigated. The results showed that the 96-h LC₅₀ values of pyraoxystrobin to embryos [2h post-fertilization (hpf)], 12h post-hatching (hph) larvae (84 hpf), 72 hph larvae (144 hpf), and adult zebrafish were 4.099, 1.069, 3.236, and 5.970µg/L, respectively. This suggests that pyraoxystrobin has very high toxicity to different life stages of zebrafish, while the newly hatched larvae constitute the most sensitive period of zebrafish to pyraoxystrobin. Decreased heart rate, hatching inhibition, growth regression, and morphological deformities were observed in zebrafish embryos after acute exposure to different concentrations of pyraoxystrobin. The rate of malformation increased in a time- and concentration-dependent manner in embryos, and the most pronounced abnormality was pericardial edema and yolk sac edema. Pyraoxystrobin (2 and 4μg/L) significantly altered the mRNA levels of genes related to mitochondrial respiratory chain and ATP synthesis (NDI, uqcrc, and ATPo6), oxidative stress (Mn-Sod, Cat, and Gpx), apoptosis (p53, Bcl2, Bax, and Cas3), and immune system (TNFα, IFN, and IL-1b) in zebrafish embryos. This result indicates that the alteration of these genes is a potential mechanism underlying the toxic effects of pyraoxystrobin on zebrafish.

ROS-mediated oligomerization of VDAC2 is associated with quinocetone-induced apoptotic cell death

Quinocetone (QCT) has been approved and widely used as an animal feed additive in China since 2003. However, investigations indicate that QCT shows potential toxicity both in vitro and in vivo. Although voltage dependent anion channel 1 (VDAC1) involved in regulating QCT-induced apoptotic cell death has been established, the role of voltage dependent anion channel 2 (VDAC2) in QCT-induced toxicity remains unclear. In this study, we showed that QCT-induced cell death was coupled to VDAC2 oligomerization. Moreover, VDAC inhibitor 4, 4'-diisothiocyano stilbene-2, 2'-disulfonic acid (DIDS) alleviated QCT-induced cell death and VDAC2 oligomerization. Meanwhile, overexpression VDAC2 aggravated QCT-induced VDAC2 oligomerization. In addition, caspase inhibitor Z-VAD-FMK and reactive oxidative species (ROS) scavenger N-acetyl-l-cysteine (NAC) apparently blocked QCT-induced cell death and VDAC2 oligomerization. Finally, overexpression N-terminal truncated VDAC2 attenuated QCT-induced VDAC2 oligomerization but had no influence on its localization to mitochondria when comparing to the full length of VDAC2. Taken together, our results reveal that ROS-mediated VDAC2 oligomerization is associated with QCT-induced apoptotic cell death. The N-terminal region of VDAC2 is required for QCT-induced VDAC2 oligomerization.

Quinocetone induces mitochondrial apoptosis in HepG2 cells through ROS-dependent promotion of VDAC1 oligomerization and suppression of Wnt1/β-catenin signaling pathway

Quinocetone (QCT) has been used as an animal feed additive in China since 2003. However, investigations indicate that QCT has potential toxicity due to the fact that it shows cytotoxicity, genotoxicity, hepatotoxicity, nephrotoxicity and immunotoxicity in vitro and animal models. Although QCT-induced mitochondrial apoptosis has been established, the molecular mechanism remains unclear. This study was aimed to investigate the role of voltage-dependent anion channel 1 (VDAC1) oligomerization and Wnt/β-catenin pathway in QCT-induced mitochondrial apoptosis. The results showed VDAC inhibitor 4, 4-diisothiocyano stilbene-2, 2-disulfonic acid (DIDS) partly compromised QCT-induced cell viability decrease (from 34.1% to 68.5%) and mitochondrial apoptosis accompanied by abating VDAC1 oligomerization, cytochrome c (Cyt c) release and the expression levels of cleaved caspase-9, -3 and poly (ADP-ribose) polymerase (PARP). Meanwhile, overexpression VDAC1 exacerbated QCT-induced VDAC1 oligomerization and Cyt c release. In addition, lithium chloride (LiCl), an activator of Wnt/β-catenin pathway, markedly attenuated QCT-induced mitochondrial apoptosis by partly restoring the expression levels of Wnt1 and β-catenin. Finally, reactive oxygen species (ROS) scavenger N-acetyl-l-cysteine (NAC) obviously blocked QCT-induced VDAC1 oligomerization and the inhibition of Wnt1/β-catenin pathway. Taken together, our results reveal that QCT induces mitochondrial apoptosis by ROS-dependent promotion of VDAC1 oligomerization and suppression of Wnt1/β-catenin pathway.

Rationally Designed CeNP@MnMoS4 Core-Shell Nanoparticles for Modulating Multiple Facets of Alzheimer's Disease

Alzheimer's disease (AD) is a complicated multifactorial syndrome. Lessons have been learned through failed clinical trials that targeting multiple key pathways of the AD pathogenesis is necessary to halt the disease progression. Here, we construct core-shell nanoparticles (CeNP@MnMoS4 ) targeting multiple key pathways of the AD pathogenesis, including elimination of toxic metal ions, decrease of oxidative stress, and promotion of neurite outgrowth. The SOD activity and copper removal capacity of CeNP@MnMoS4 -n (n represents the number of layers of MnMoS4 , n=1-5) was investigated in vitro. We found that CeNP@MnMoS4 -3 made an excellent balance between SOD activity and copper removal capacity. The effect of CeNP@MnMoS4 -3 on Cu(2+) -induced Aβ aggregation was studied by gel electrophoresis, transmission electron microscope (TEM), and atomic force microscopy (AFM). Compared with MnMoS4 or CeNP alone, a synergistic effect was observed. Moreover, CeNP@MnMoS4 -3 promoted neurite outgrowth in a dose-dependent manner. Taken together, the results reported in this work show the potential of new multifunctional core-shell nanoparticles as AD therapeutics.

Oxidative stress in dairy cows naturally infected with the lungworm Dictyocaulus viviparus (Nematoda: Trichostrongyloidea)

The aim of this study was to analyse the oxidative and anti-oxidant status in serum samples from dairy cows naturally infected by Dictyocaulus viviparus and its relation with pathological analyses. The diagnosis of the disease was confirmed by necropsy of one dairy cow with heavy infection by the parasite in the lungs and bronchi. Later, blood and faeces were collected from another 22 cows from the same farm to measure reactive oxygen species (ROS) levels, thiobarbituric acid-reactive substances (TBARS), catalase (CAT) and superoxide dismutase (SOD) activities on day 0 (pre-treatment) and day 10 (post-treatment with eprinomectin). Faecal examination confirmed the infection in all lactating cows. However, the number of D. viviparus larvae per gram of faeces varied between animals. Cows showed different degrees of severity according to respiratory clinical signs of the disease (cough and nasal secretion). Further, they were classified and divided into two groups: those with mild (n = 10) and severe disease (n = 12). Increased levels of TBARS (P < 0.001), ROS (P = 0.002) and SOD activity (P < 0.001), as well as reduced CAT activity (P < 0.001) were observed in cows with severe clinical signs of the disease compared to those with mild clinical signs. Eprinomectin treatment (day 10) caused a reduction of ROS levels (P = 0.006) and SOD activity (P < 0.001), and an increase of CAT activity (P = 0.05) compared to day 0 (pre-treatment). TBARS levels did not differ with treatment (P = 0.11). In summary, increased ROS production and lipid peroxidation altered CAT and SOD activities, as an adaptive response against D. viviparus infection, contributing to the occurrence of oxidative stress and severity of the disease. Treatment with eprinomectin eliminated the infection, and thus minimized oxidative stress in dairy cows.

From immunotoxicity to carcinogenicity: the effects of carbamate pesticides on the immune system

The immune system can be the target of many chemicals, with potentially severe adverse effects on the host's health. In the literature, carbamate (CM) pesticides have been implicated in the increasing prevalence of diseases associated with alterations of the immune response, such as hypersensitivity reactions, some autoimmune diseases and cancers. CMs may initiate, facilitate, or exacerbate pathological immune processes, resulting in immunotoxicity by induction of mutations in genes coding for immunoregulatory factors and modifying immune tolerance. In the present study, direct immunotoxicity, endocrine disruption and inhibition of esterases activities have been introduced as the main mechanisms of CMs-induced immune dysregulation. Moreover, the evidence on the relationship between CM pesticide exposure, dysregulation of the immune system and predisposition to different types of cancers, allergies, autoimmune and infectious diseases is criticized. In addition, in this review, we will discuss the relationship between immunotoxicity and cancer, and the advances made toward understanding the basis of cancer immune evasion.