The level of H2 O2 -type oxidative stress regulates virulence of Theileria-transformed leukocytes

International audienceTheileria annulata infects predominantly macro-phages, and to a lesser extent B cells, and causes a widespread disease of cattle called tropical theileriosis. Disease-causing infected macro-phages are aggressively invasive, but this viru-lence trait can be attenuated by long-term culture. Attenuated macrophages are used as live vaccines against tropical theileriosis and via their charac-terization one gains insights into what host cell trait is altered concomitant with loss of virulence. We established that sporozoite infection of mono-cytes rapidly induces hif1-α transcription and that constitutive induction of HIF-1α in transformed leukocytes is parasite-dependent. In both infected macrophages and B cells induction of HIF-1α acti-vates transcription of its target genes that drive host cells to perform Warburg-like glycolysis. We propose that Theileria-infected leukocytes main-tain a HIF-1α-driven transcriptional programme typical of Warburg glycolysis in order to reduce as much as possible host cell H 2O2 type oxidative stress. However, in attenuated macrophages H2O2 production increases and HIF-1α levels conse-quently remained high, even though adhesion and aggressive invasiveness diminished. This indicates that Theileria infection generates a host leukocytes hypoxic response that if not properly controlled leads to loss of virulence

Mangafodipir Protects against Hepatic Ischemia-Reperfusion Injury in Mice

Mangafodipir is a contrast agent used in magnetic resonance imaging that concentrates in the liver and displays pleiotropic antioxidant properties. Since reactive oxygen species are involved in ischemia-reperfusion damages, we hypothesized that the use of mangafodipir could prevent liver lesions in a mouse model of hepatic ischemia reperfusion injury. Mangafodipir (MnDPDP) was compared to ischemic preconditioning and intermittent inflow occlusion for the prevention of hepatic ischemia-reperfusion injury in the mouse.Mice were subjected to 70% hepatic ischemia (continuous ischemia) for 90 min. Thirty minutes before the ischemic period, either mangafodipir (10 mg/kg) or saline was injected intraperitoneally. Those experimental groups were compared with one group of mice preconditioned by 10 minutes' ischemia followed by 15 minutes' reperfusion, and one group with intermittent inflow occlusion. Hepatic ischemia-reperfusion injury was evaluated by measurement of serum levels of aspartate aminotransferase (ASAT) activity, histologic analysis of the livers, and determination of hepatocyte apoptosis (cytochrome c release, caspase 3 activity). The effect of mangafodipir on the survival rate of mice was studied in a model of total hepatic ischemia.<0.01), and by higher rates of survival in treated than in untreated animals (P<0.001). The level of protection by mangafodipir was similar to that observed following intermittent inflow occlusion and higher than after ischemic preconditioning.Mangafodipir is a potential new preventive treatment for hepatic ischemia-reperfusion injury

Chalcone-Coumarin derivatives as potential anti-cancer drugs: an in vitro and in vivo investigation

Cancer cells display an overproduction of reactive oxygen species resulting from an exaggerated intrinsic oxidative stress. However, the concept of deleterious oxidants versus beneficial antioxidants has recently evolved. Indeed, molecules like natural coumarins have shown anti-oxidant or pro-oxidant properties depending on their intracellular concentration. Therefore, we have investigated the structure-activity relationship of a variety of coumarin derivatives in terms of cytotoxicity towards human and murine carcinoma cell lines (HT29, HepG2, A549, MCF7, OVCAR and CT26). Amongst those compounds, (E)-7-methoxy-4-(3-oxo-3- phenylprop-1-enyl)-2H-chromen-2-one and (E)-7-hydroxy-4-(3-(4-hydroxyphenyl)-3-oxoprop-1-enyl)-2H-chromen-2-one displayed the most potent cytotoxic effect on colon cancer cells, CT26, (IC50=4.9µM) linked to their pro-oxidant properties. Those compounds triggered the in vitro production of reactive oxygen species by tumor cells, leading to their death through a necrotic process. In vivo, molecules also slowed down tumor growth by 65.7% and 35.4%, respectively, without inducing significant side effects

Prevention of lipid peroxidation following ischemia-reperfusion of the liver using on mangafodipir and intermittent clamping.

<p>The concentrations of 4-hydroxyalkenals (4-HNE) and malondialdehyde (MDA) were measured spectrophotometrically in whole liver homogenates. The level of lipid peroxidation was expressed as the amounts of 4-HNE + MDA per mg of proteins. Bars represent means ± SEM; nine mice in each group.</p

Mangafodipir and intermittent clamping prevent the increase in transaminase activities following reperfusion injury.

<p>Serum levels of aspartate amino-transferase activities (ASAT) served as markers of hepatocyte injury. ASAT levels were measured after 24 hours of reperfusion. Bars represent means ± SEM, nine mice in each group.</p

Increasing the survival rate of mice by mangafodipir following reperfusion injury of the liver.

*<p>Animal survival was evaluated using the model of total hepatic ischemia (37).</p><p>The rate of mouse survival was evaluated in control group (90 minutes of ischemia; n = 9) and in control group with intraperitoneal administration of 10 mg/kg of mangafodipir 30 minutes prior to ischemia (n = 9) <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0027005#pone.0027005-Yadav1" target="_blank">[40]</a>. For the survival time courses, animals were sacrificed when they appeared moribund.</p

Prevention of glutathione depletion in the mitochondria (A) and in the cytoplasm (B) of hepatocytes following reperfusion injury.

<p>The concentrations of glutathione in cytoplasm and mitochondria of mouse liver were measured spectrophotometrically in whole liver homogenates. The levels of reduced gluthatione were expressed as pmol per 10 µg of proteins. Bars represent means ± SEM, nine mice in each group. The O2°- depletion in the mitochondria (C) of HepG2 cells induced by mangafodipir (400 µM) was assessed in a kinetic experiment. Immunofluorescence microscopy of HepG2 cells stained with oxidation of dihydroethidium (DHE) and treated for 18 h or not with mangafodipir. (D–E) A decreased intensity of cytosol with mangafodipir in mangafodipir treated cells was observed.</p

Prevention of hepatocytes apoptosis following reperfusion injury.

<p>The mitochondrial/cytosol cytochrome c ratio (A) and caspase-3 activities were measured in the livers of the various experimental groups and controls. Caspase-3 like activities were expressed as Units per mg of proteins. Bars represent means ± SEM, nine mice in each group.</p

Mangafodipir and intermittent clamping prevent histological lesions of the liver following reperfusion injury.

<p>Hematoxylin-eosin-stained sections were used for histopathological evaluation of hepatic injuries. The sections were examined at 400-fold magnification. Representative livers from normal BALB/c mice (A), Sham-operated mice (B), ninety minutes' ischemia control group (C), Mangafodipir (MnDPDP)-treated group (D), IP-treated group (E) and IC-treated group (F).</p