Search

Immunotherapy is a promising antitumor strategy that can successfully be combined with current anticancer treatment. In this study, arsenic trioxide (As(2)O(3)) was shown to increase the antitumor immune response in CT26 colon tumor-bearing mice through the modulation of regulatory T cell (T(reg)) numbers. As(2)O(3) induced T(reg)-selective depletion in vitro. In vivo, tumor-bearing mice injected with 1 mg/kg As(2)O(3) showed a significant decrease in the T(reg)/CD4 cell ratio and in absolute T(reg) count versus controls. As(2)O(3) exerted antitumor effects only in immunocompetent mice and enhanced adoptive immunotherapy effects. Inhibition of As(2)O(3)-induced T(reg) depletion by the NO synthase inhibitor N(G)-nitro-l-arginine methyl ester and the superoxide dismutase mimic manganese [III] tetrakis-(5, 10, 15, 20)-benzoic acid porphyrin suggested that it was mediated by oxidative and nitrosative stress. The differential effect of As(2)O(3) on T(reg) versus other CD4 cells may be related to differences in the cells' redox status, as indicated by significant differences in 2'7'dichlorodihydrofluorescein diacetate and 4,5-diaminofluorescein diacetate fluorescence levels. In conclusion, these results show for the first time, to our knowledge, that low doses As(2)O(3) can delay solid tumor growth by depleting T(regs) through oxidative and nitrosative bursts, and suggest that As(2)O(3) could be used to enhance the antitumor activity of adoptive immunotherapy strategies in human cancer.

Renal ischaemia-reperfusion injury (IRI) is consecutive to tissue oxidative damage and cell apoptosis that lead to acute renal failure (ARF) in renal allografts. The aim of this study was to investigate the beneficial effects of a pretreatment by clopidogrel on renal IRI in mice. IRI was induced by bilateral renal ischaemia for 45 min followed by reperfusion. Sixty-two healthy male BALB/c mice were randomly assigned to one of the following groups: PBS + ischaemia-reperfusion (IR); clopidogrel + IR; PBS + sham IR; clopidogrel + sham IR. Clopidogrel (25 mg/kg) or PBS was administered per os to the animals via a gastric cannula 24 h before operation. All mice were given a single dose of clopidogrel or PBS. Renal function histological damage, renal cell apoptosis, renal antioxidant activities, and CD41 expression were determined 24 h after reperfusion. The survival rates were evaluated over 7 days. Animals pretreated with clopidogrel had lower plasma levels of blood urea nitrogen (BUN) and creatinine, lower histopathological scores, and improved survival rates following IR. Renal cell apoptosis induced by IR was decreased in kidneys of mice pretreated by clopidogrel, with an increase in Bcl-2 and Bcl-xL expression and a decrease in caspase-3, caspase-8, and Bax expression. Renal reduced glutathione, superoxide dismutase, and catalase activities were unmodified by the pretreatment with clopidogrel. However, clopidogrel resulted in an increased total antioxidant capacity of the kidney. Furthermore, pretreatment by clopidogrel decreased the number of CD41-positive cells. Thus, clopidogrel exerts protective effects on renal IRI in mice by abrogating renal cell apoptosis as a consequence of improved renal antioxidant capacity and could be tried as a novel therapeutic tool in renal IRI., (Copyright © 2011 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.)

Oxidative stress plays a role in the regulation of cancer cell metastasis which involves cell invasion and adhesion that could be supported by ADAM proteins through the activities of their metalloprotease and disintegrin domains. We hypothesized that oxidative stress could act through the induction of ADAM9 protein in some cancer cells. Indeed, Western blot analysis for ADAM9 performed on A549 cells exposed to H(2) O(2) reveals a dose-dependent induction of two proteins (80 and 68 kDa) correlated with a sharp increase of the ADAM protease activity measured in supernatant while the activity measured on the cell layer was slightly affected. The 80kDa protein corresponds to the mature form of ADAM9. Immunoprecipitation analysis performed on concentrated supernatants revealed that the 68 kDa protein is a secreted form of ADAM9. When exposed to H(2) O(2) , A549 cells cocultured with confluent endothelial vascular cells resulted in a 5.5 fold (p < 0.001) increase in the number of adherent cells. Similarly, matrigel assay revealed a 3.25 fold (p < 0.01) increase in the number of invasive cells. The suppression of ADAM9 expression by specific small interfering RNA reduced oxidative stress-induced invasiveness and adhesiveness. These functions could be mediated by an interaction between ADAM9 and β1 integrin because each of them were inhibited when the experiment is performed in presence of mAbs targeting ADAM9 ectodomain or β1-integrin. These results emphasize the importance of oxidative stress in the regulation of cancer cell metastasis and suggest that ADAM9 and its secreted isoform can be important determinants in the ability of cancer cells to disseminate., (Copyright © 2010 UICC.)

Endometriosis is associated with chronic inflammation, and reactive oxygen species (ROS) are proinflammatory mediators that modulate cell proliferation. We have investigated whether the dysregulation of ROS production in endometriotic cells correlates with a pro-proliferative phenotype and can explain the spreading of this disease. Stromal and epithelial cells were purified from ovarian endometrioma and eutopic endometrium from 14 patients with endometriosis to produce four primary cell lines from each patient. ROS production, detoxification pathways, cell proliferation, and mitogen-activated protein kinase pathway activation were studied and compared with epithelial and stromal cell lines from 14 patients without endometriosis. Modulation of the proliferation of endometriosis by N-acetyl-cysteine, danazol, and mifepristone was tested in vitro and in 28 nude mice implanted with endometriotic tissue of human origin. Endometriotic cells displayed higher endogenous oxidative stress with an increase in ROS production, alterations in ROS detoxification pathways, and a drop in catalase levels, as observed for tumor cells. This increase in endogenous ROS correlated with increased cellular proliferation and activation of ERK1/2. These phenomena were abrogated by the antioxidant molecule N-acetyl-cysteine both in vitro and in a mouse model of endometriosis. Human endometriotic cells display activated pERK, enhanced ROS production, and proliferative capability. Our murine model shows that antioxidant molecules could be used as safe and efficient treatments for endometriosis.

Systemic sclerosis (SSc) is a connective tissue disorder of great clinical heterogeneity. Its pathophysiology remains unclear. Our aim was to evaluate the relative roles of reactive oxygen species (ROS) and of the immune system using an original model of SSc. BALB/c and immunodeficient BALB/c SCID mice were injected s.c. with prooxidative agents (hydroxyl radicals, hypochlorous acid, peroxynitrites, superoxide anions), bleomycin, or PBS everyday for 6 wk. Skin and lung fibrosis were assessed by histological and biochemical methods. Autoantibodies were detected by ELISA. The effects of mouse sera on H(2)O(2) production by endothelial cells and on fibroblast proliferation, and serum concentrations in advanced oxidation protein products (AOPP) were compared with sera from patients with limited or diffuse SSc. We observed that s.c. peroxynitrites induced skin fibrosis and serum anti-CENP-B Abs that characterize limited SSc, whereas hypochlorite or hydroxyl radicals induced cutaneous and lung fibrosis and anti-DNA topoisomerase 1 autoantibodies that characterize human diffuse SSc. Sera from hypochlorite- or hydroxyl radical-treated mice and of patients with diffuse SSc contained high levels of AOPP that triggered endothelial production of H(2)O(2) and fibroblast hyperproliferation. Oxidized topoisomerase 1 recapitulated the effects of whole serum AOPP. SCID mice developed an attenuated form of SSc, demonstrating the synergistic role of the immune system with AOPP in disease propagation. We demonstrate a direct role for ROS in SSc and show that the nature of the ROS dictates the form of SSc. Moreover, this demonstration is the first that shows the specific oxidation of an autoantigen directly participates in the pathogenesis of an autoimmune disease.

Objective: Plasma from septic shock patients can induce production of reactive oxygen species (ROS) by human umbilical vein endothelial cells (HUVEC) in vitro. How endothelial cells defend themselves against ROS under increased oxidative stress has not yet been examined. This study investigates the antioxidant defenses of HUVEC exposed to plasma obtained from either septic shock patients or healthy volunteers., Design: Prospective, observational study., Setting: Medical intensive care unit in a university hospital., Patients: Twenty-five patients with septic shock and 10 healthy volunteers., Interventions: Blood samples were collected within the first 24 hrs of septic shock. In vitro HUVEC production of ROS was studied by spectrofluorimetry using 2',7'-dichlorodihydrofluorescein diacetate fluorescent dye. Reactive nitrogen species were also assessed. Intracellular reduced glutathione (GSH) levels were measured using monochlorobimane fluorescent dye. Activity of catalase and superoxide dismutase in HUVEC were also measured. Cell death was assessed using YOPRO fluorescent dye and the MTT assay., Measurements and Results: On admission, the septic shock population's mean age was 55 yrs old, the mean Sequential Organ Failure Assessment score was 12, mean simplified acute physiology score was 50, and intensive care unit mortality rate was 45%. Evaluation of HUVEC antioxidant defenses showed a significantly decreased GSH level, increased catalase activity, and unchanged superoxide dismutase activity. ROS levels and cell death were significantly reduced when cells were pretreated with N-acetylcysteine or GSH, but no changes in reactive nitrogen species were observed., Conclusion: This study demonstrates that plasma-induced ROS production by HUVEC is associated with an intracellular decrease in reduced GSH. Both ROS levels and cell death decreased when N-acetylcysteine or GSH were added before exposing the cells to plasma. These data suggest a pivotal role of alterations in GSH in damage caused by sepsis-generated ROS in endothelial cell.

Background: Anticancer drugs act by increasing intracellular hydrogen peroxide levels. Mangafodipir, a superoxide dismutase (SOD) mimic with catalase and glutathione reductase activities, protects normal cells from apoptosis induced by H2O2. We investigated its and other oxidative stress modulators' effects on anticancer drug activity in vitro and in vivo., Methods: Cell lysis and intracellular reactive oxygen species levels were assessed in vitro in human leukocytes from healthy subjects and in murine CT26 colon cancer cells. Cells were exposed to the chemotherapeutic agents paclitaxel, oxaliplatin, or 5-fluorouracil, either in the presence or absence of mangafodipir and other oxidative stress modulators. Cell viability was evaluated by the methylthiazoletetrazolium assay. The effects of mangafodipir and other oxidative stress modulators on peripheral blood counts and on tumor growth were studied in BALB/c mice that were implanted with CT26 tumors and treated with 20 mg/kg paclitaxel. Survival of BALB/c mice infected with Staphylococcus aureus was also examined by treatment group. Statistical tests were two-sided., Results: In vitro lysis of leukocytes exposed to paclitaxel, oxaliplatin, or 5-fluorouracil in combination with mangafodipir was decreased by 46% (95% confidence interval [CI] = 44% to 48%), 30.5% (95% CI = 29% to 32%), and 15% (95% CI = 10% to 20%), compared with lysis of cells treated with anticancer agent alone. Mangafodipir also statistically significantly enhanced in vitro anticancer drug cytotoxicity toward CT26 cancer cells. In vivo, mangafodipir protected mice against paclitaxel-induced leukopenia. Moreover, the survival rate of mice infected with S. aureus and treated with paclitaxel was higher when mangafodipir was also administered (survival: 3 of 17 versus 14 of 17, P < .001). In addition, mangafodipir amplified the inhibitory effect of paclitaxel on CT26 tumor growth in mice., Conclusions: Mangafodipir decreased hematotoxicity and enhanced cytotoxicity of anticancer agents.