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Previously, we reported that 3H-1,2-dithiole-3-thione (D3T), an Nrf2 activator, acted as a potential chemoprotectant against lipopolysaccharide (LPS)-induced mortality in mice. In view of the critical involvement of macrophages in the pathogenesis of LPS-induced endotoxemia, in the present study, we investigated the protective effects of D3T on LPS-induced proinflammatory responses in cultured murine RAW 264.7 macrophage cell line and primary peritoneal macrophages and the potential involvement of antioxidant induction, NF-κB, and Nrf2. We showed that treatment with D3T resulted in increased levels of a series of antioxidants in RAW 264.7 cells in a concentration-dependent manner. These included the reduced form of glutathione, glutathione peroxidase, glutathione reductase, glutathione S-transferase, and NADPH:quinone oxidoreductase 1. Catalase was also potently induced by D3T which, however, did not show a concentration dependency. Concurrent with the ability to induce the above cellular antioxidants, D3T pretreatment of RAW 264.7 cells also led to a concentration-dependent suppression of LPS-induced interleukin-1beta (IL-1β) production and nitric oxide release. LPS-stimulated tumor necrosis factor-alpha (TNF-α) production was also suppressed by D3T, but to a much lesser extent. Using NF-κB reporter gene-expressing RAW 264.7 cells, we further showed that D3T pretreatment also suppressed LPS-induced NF-κB activation. To investigate the potential involvement of Nrf2, a chief regulator of cellular antioxidant genes, we used peritoneal macrophages isolated from Nrf2

Cerium oxide nanoparticles, also known as nanoceria, possess antioxidative and anti-inflammatory activities in animal models of inflammatory disorders, such as sepsis. However, it remains unclear how nanoceria affect cellular superoxide fluxes in macrophages, a critical type of cells involved in inflammatory disorders. Using human ML-1 cell-derived macrophages, we showed that nanoceria at 1–100 μg/ml potently reduced superoxide flux from the mitochondrial electron transport chain (METC) in a concentration-dependent manner. The inhibitory effects of nanoceria were also shown in succinate-driven mitochondria isolated from the macrophages. Furthermore, nanoceria markedly mitigated the total intracellular superoxide flux in the macrophages. These data suggest that nanoceria could readily cross the plasma membrane and enter the mitochondrial compartment, reducing intracellular superoxide fluxes in unstimulated macrophages. In macrophages undergoing respiratory burst, nanoceria also strongly reduced superoxide flux from the activated macrophage plasma membrane NADPH oxidase (NOX) in a concentration-dependent manner. Token together, the results of the present study demonstrate that nanoceria can effectively diminish superoxide fluxes from both METC and NOX in human macrophages, which may have important implications for nanoceria-mediated protection against inflammatory disease processes.

Epidemiological studies have exhibited a strong correlation between exposure to air pollution and deaths due to vascular diseases such as atherosclerosis. Benzo-a-pyrene-1,6-quinone (BP-1,6-Q) is one of the components of air pollution. This study was to examine the role of GSH in BP-1,6-Q mediated cytotoxicity in human EA.hy96 endothelial cells and demonstrated that induction of cellular glutathione by a potent triterpenoid, CDDO-Im (1-[2-cyano-3-,12-dioxooleana-1,9(11)-dien-28-oyl]imidazole), protects cells against BP-1,6-Q induced protein and lipid damage. Incubation of EA.hy926 endothelial cells with BP-1,6-Q caused a significant increase in dose-dependent cytotoxicity as measured by LDH release assay and both apoptotic and necrotic cell deaths as measured by flow cytometric analysis. Incubation of EA.hy926 endothelial cells with BP-1,6-Q also caused a significant decrease in cellular GSH levels. The diminishment of cellular GSH by buthionine sulfoximine (BSO) potentiated BP-1,6-Q-induced toxicity significantly suggesting a critical involvement of GSH in BP-1,6-Q induced cellular toxicity. GSH-induction by CDDO-Im significantly protects cells against BP-1,6-Q induced protein and lipid damage as measured by protein carbonyl (PC) assay and thiobarbituric acid reactive substances (TBARS) assay, respectively. However, the co-treatment of cells with CDDO-Im and BSO reversed the cytoprotective effect of CDDO-Im on BP-1,6-Q-mediated lipid peroxidation and protein oxidation. These results suggest that induction of GSH by CDDO-Im might be the important cellular defense against BP-1,6-Q induced protein and lipid damage. These findings would contribute to better understand the action of BP-1,6-Q and may help to develop novel therapies to protect against BP-1,6-Q-induced atherogenesis.

Peroxiredoxin (Prx) refers to a family of thiol-dependent peroxidases that decompose hydrogen peroxide, lipid hydroperoxides, as well as peroxynitrite, and protect against oxidative and inflammatory stress. There are six mammalian Prx isozymes (Prx1-6), classified as typical 2-Cys, atypical 2-Cys, or 1-Cys Prxs based on the mechanism and the number of cysteine residues involved during catalysis. In addition to their well-established peroxide-scavenging activity, some Prxs also participate in the regulation of various cell signaling pathways. Extensive animal studies employing primarily gene knockout models provide substantial evidence supporting a critical protective role of Prxs in various disease processes involving oxidative and inflammatory stress. This review surveys recent research findings, published primarily in influential journals, on the involvement of various Prx isozymes in protecting against cardiovascular injury and related disorders, including diabetes, metabolic syndromes, and sepsis, whose pathophysiology all intimately involves oxidative stress and inflammation.

Strong epidemiological evidence supports the association between increased air pollution and the risk of developing atherosclerotic cardiovascular diseases (CVDs). However, the mechanism remains unclear. As an environmental air pollutant and benzo-a-pyrene (BP) metabolite, BP-1,6-quinone (BP-1,6-Q) is present in the particulate phase of air pollution. This study was undertaken to examine the redox activity of BP-1,6-Q and mechanisms associated with it using EA.hy926 endothelial cells. BP-1,6-Q at 0.01–1 μM significantly stimulated the production of reactive oxygen species (ROS)·in intact cells and isolated mitochondria. Furthermore, BP-1,6-Q-induced ROS was altered by mitochondrial electron transport chain (METC) inhibitors of complex I (rotenone) and complex III (antimycin A), denoting the involvement of mitochondrial electron transport chain (METC) in BP-1,6-Q mediated ROS production. In METC deficient cells, interestingly, BP-1,6-Q-mediated ROS production was enhanced, suggesting that overproduction of ROS by BP-1,6-Q is not only produced from mitochondria but can also be from the cell outside of mitochondria (extramitochondrial). BP-1,6-Q also triggered endothelial-monocyte interaction and stimulated expression of vascular adhesion molecule-1 (VCAM-1). In conclusion, these results demonstrate that BP-1,6-Q can generate ROS within both mitochondria and outside of mitochondria, resulting in stimulation of adhesion of monocytes to endothelial cells, a key event in the pathogenesis of atherosclerosis.

Objective To investigate the potential compensatory effects of hOGG1 and hMTH1 in the repair of oxidative DNA damage. Methods The hOGG1 and hMTH1 gene knockdown human embryonic pulmonary fibroblast cell lines were established by lentivirus-mediated RNA interference. The messenger RNA (mRNA) levels of hOGG1 and hM1TH1 were analyzed by the real-time polymerase chain reaction, and 8-hydroxy-2′-deoxyguanosine (8-oxo-dG) formation was analyzed in a high-performance liquid chromatography-electrochemical detection system. Results The hOGG1 and hMTH1 knockdown cells were obtained through blasticidin selection. After transfection of hOGG1 and hMTH1 small interfering RNA, the expression levels of the mRNA of hOGG1 and hMTH1 genes were decreased by 97.2% and 96.2%, respectively. The cells then were exposed to 100 μmol/L of hydrogen peroxide (H2O2) for 12 h to induce oxidative DNA damage. After H2O2 exposure, hMTH1 mRNA levels were increased by 25% in hOGG1 gene knockdown cells, whereas hOGG1 mRNA levels were increased by 52% in hMTH1 gene knockdown cells. Following the treatment with H2O2, the 8-oxo-dG levels in the DNA of hOGG1 gene knockdown cells were 3.1-fold higher than those in untreated HFL cells, and 1.67-fold higher than those in H2O2-treated wild-type cells. The 8-oxo-dG levels in hMTH1 gene knockdown cells were 2.3-fold higher than those in untreated human embryonic pulmonary fibroblast cells, but did not differ significantly from those in H2O2-treated wild-type cells. Conclusion Our data suggested that hOGG1 could compensate for hMTH1 during oxidative DNA damage caused by H2O2, whereas hMTH1 could not compensate sufficiently for hOGG1 during the process.

Inflammatory bowel disease (IBD) comprises primarily the chronic relapsing inflammatory disorders, Crohn's disease and ulcerative colitis, with the former affecting any part of the gastrointestinal tract and the latter mainly afflicting the colon. The precise etiology of IBD remains unclear, and it is thought that interactions among various factors, including genetic factors, the host immune system and environmental factors, cause disruption of intestinal homeostasis, leading to dysregulated inflammatory responses of the gut. As inflammation is intimately related to formation of reactive intermediates, including reactive oxygen and nitrogen species (ROS/RNS), oxidative stress has been proposed as a mechanism underlying the pathophysiology of IBD. This review is intended to summarize succinctly recent new experimental and clinical evidence supporting oxidative stress as a pathophysiological component of IBD and point to the potential of using antioxidant compounds as promising therapeutic modalities of human IBD. The sources of ROS/RNS and the redox signaling mechanism underlying oxidative stress and inflammation in IBD are discussed to provide insight into the molecular basis of oxidative stress as a pathophysiological factor in IBD.

Alcoholic liver disease (ALD) is a major cause of morbidity and mortality worldwide. The spectrum of ALD ranges from fatty liver to alcoholic hepatitis and cirrhosis, which may eventually lead to the development of hepatocellular carcinoma. In developed countries as well as many developing nations, ALD is a major cause of end-stage liver disease that requires liver transplantation. The most effective therapy for ALD is alcohol abstinence; however, for individuals with severe forms of ALD and those in whom alcohol abstinence is not achievable, targeted therapies are absolutely necessary. In this context, advances of our understanding of the pathophysiology of ALD over the past two decades have contributed to the development of therapeutic modalities (e.g., pentoxifylline and corticosteroids) for the disease though the efficacy of the available treatments remains limited. This article is intended to succinctly review the recent experimental and clinical findings regarding the involvement of oxidative stress and redox signaling in the pathophysiology of ALD and the development of mechanistically-based antioxidant modalities to target the oxidative stress and redox signaling mechanisms of ALD. The biochemical and cellular sources of reactive oxygen and nitrogen species (ROS/RNS) and the dysregulated redox signaling pathways associated with alcohol consumption are particularly discussed to provide insight into the molecular basis of hepatic cell dysfunction and destruction as well as tissue remodeling underlying ALD.

Acrolein is a ubiquitous unsaturated aldehyde has been implicated in the pathogenesis of various neurological disorders. However, limited study has been conducted into potential therapeutic protection and underlying mechanism against acrolein-induced cytotoxicity via upregulation of cellular aldehyde-detoxification defenses. In this study we have utilized RA-differentiated human SH-SY5Y cells and primary human astrocytes to investigate the induction of glutathione (GSH) by the synthetic triterpenoid 2-cyano-3,12-dixooleana-1,9-dien-28-imidazolide (CDDO-Im) and the protective effects CDDO-Im-mediated antioxidant defenses on acrolein toxicity. Acrolein exposure to RA-differentiated SH-SY5Y cells resulted in a significant time dependent depletion of cellular GSH preceding a reduction in cell viability and LDH release. Further, we demonstrated the predominance of cellular GSH in protection against acrolein-induced cytotoxicity. Buthionine sulfoximine (BSO) at 25μM dramatically depleted GSH and significantly potentiated acrolein-induced cytotoxicity. Pretreatment of the cells with 100nM CDDO-Im afforded a dramatic protection against acrolein-induced cytotoxicity. Pretreatment of BSO and CDDO was found to prevent the CDDO-Im-mediated GSH induction and partially reversed the cytoprotective effects of CDDO-Im against acrolein cytotoxicity. Overall, this study represents for the first time the CDDO-Im mediated upregulation of GSH is a predominant mechanism against acrolein-induced neurotoxicity.