Persistent oxidative stress following renal ischemia-reperfusion injury increases ANG II hemodynamic and fibrotic activity

ANG II is a potent renal vasoconstrictor and profibrotic factor and its activity is enhanced by oxidative stress. We sought to determine whether renal oxidative stress was persistent following recovery from acute kidney injury (AKI) induced by ischemia-reperfusion (I/R) injury in rats and whether this resulted in increased ANG II sensitivity. Rats were allowed to recover from bilateral renal I/R injury for 5 wk and renal blood flow responses were measured. Post-AKI rats showed significantly enhanced renal vasoconstrictor responses to ANG II relative to sham-operated controls and treatment of AKI rats with apocynin (15 mM, in the drinking water) normalized these responses. Recovery from AKI for 5 wk resulted in sustained oxidant stress as indicated by increased dihydroethidium incorporation in renal tissue slices and was normalized in apocynin-treated rats. Surprisingly, the renal mRNA expression for common NADPH oxidase subunits was not altered in kidneys following recovery from AKI; however, mRNA screening using PCR arrays suggested that post-AKI rats had decreased renal Gpx3 mRNA and an increased expression other prooxidant genes such as lactoperoxidase, myeloperoxidase, and dual oxidase-1. When rats were infused for 7 days with ANG II (100 ng·kg(-1)·min(-1)), renal fibrosis was not apparent in sham-operated control rats, but it was enhanced in post-AKI rats. The profibrotic response was significantly attenuated in rats treated with apocynin. These data suggest that there is sustained renal oxidant stress following recovery from AKI that alters both renal hemodynamic and fibrotic responses to ANG II, and may contribute to the transition to chronic kidney disease following AKI.     

Non-invasive limb ischemic pre-conditioning reduces oxidative stress and attenuates myocardium ischemia-reperfusion injury in diabetic rats

This study was to explore whether repeated non-invasive limb ischemic pre-conditioning (NLIP) can confer an equivalent cardioprotection against myocardial ischemia-reperfusion (I/R) injury in acute diabetic rats to the extent of conventional myocardial ischemic pre-conditioning (MIP) and whether or not the delayed protection of NLIP is mediated by reducing myocardial oxidative stress after ischemia-reperfusion. Streptozotocin-induced diabetic rats were randomized to four groups: Sham group, the I/R group, the MIP group and the NLIP group. Compared with the I/R group, both the NLIP and MIP groups showed an amelioration of ventricular arrhythmia, reduced myocardial infarct size, increased activities of total superoxide dismutase (SOD), manganese-SOD and glutathione peroxidase, increased expression of manganese-SOD mRNA and decreased xanthine oxidase activity and malondialdehyde concentration (All p < 0.05 vs I/R group). It is concluded that non-invasive limb ischemic pre-conditioning reduces oxidative stress and attenuates myocardium ischemia-reperfusion injury in diabetic rats.     

Time-dependent platelet-vessel wall interactions induced by intestinal ischemia-reperfusion

Platelets roll and adhere in venules exposed to ischemia-reperfusion (I/R). This platelet-endothelial adhesion may influence leukocyte trafficking because platelet depletion decreases I/R-induced leukocyte emigration. The objectives of this study were 1) to assess the time course of platelet adhesion in the small bowel after I/R and 2) to determine the roles of endothelial and/or platelet P-selectin and P-selectin glycoprotein ligand-1 (PSGL-1) in this adhesion. The adhesion of fluorescently labeled platelets was monitored by intravital microscopy in postcapillary venules exposed to 45 min of ischemia and up to 8 h of reperfusion. Peak platelet adhesion was observed at 4 h of reperfusion. To assess the contributions of platelet and endothelial cell P-selectin, platelets from P-selectin-deficient and wild-type mice were infused into wild-type and P-selectin-deficient mice, respectively. Platelets deficient in P-selectin exhibited low levels of adhesion comparable to that in sham-treated animals. In the absence of endothelial P-selectin, platelet adhesion was reduced by 65%. Treatment with a blocking antibody against PSGL-1 reduced adhesion by 57%. These results indicate that I/R induces a time-dependent platelet-endothelial adhesion response in postcapillary venules via a mechanism that involves PSGL-1 and both platelet and endothelial P-selectin, with platelet P-selectin playing a greater role.     

Curcumin protects cardiac cells against ischemia-reperfusion injury: effects on oxidative stress, NF-kappaB, and JNK pathways

In this study we explored the effects of curcumin in cardiac cells subjected to a protocol simulating ischemia-reperfusion (IR). Curcumin (10 microM) was administered before ischemia (pretreatment) or at the moment of reperfusion (posttreatment) and its effects were compared to those produced by a reference antioxidant (Trolox) with an equal antioxidant capacity. IR cardiac cells showed clear signs of oxidative stress, impaired mitochondrial activity, and a marked development of both necrotic and apoptotic processes; at the same time, increases in NF-kappaB nuclear translocation and JNK phosphorylation were observed. Curcumin pretreatment was revealed to be the most effective in attenuating all these modifications and, in particular, in reducing the death of IR cells. This confirms that the protective effect of curcumin is not related simply to its antioxidant properties but involves other mechanisms, notably interactions in the NF-kappaB and JNK pathways. These findings suggest that curcumin administration, in particular before the hypoxic challenge, represents a promising approach to protecting cardiac cells against IR injury. In this scenario our results point out the importance of the chronology for the outcome of the treatment and provide a differential valuation of the degree of protection that curcumin can exert by its antioxidant activity or by other mechanisms.     

Lung ischemia-reperfusion injury in awake sheep: protection with verapamil.

We caused unilateral lung ischemia-reperfusion injury in awake sheep by simultaneously occluding the left pulmonary artery and left main stem bronchus for 12 h. The occluded left lung was inflated with nitrogen. Reperfusion resulted in an elevation of lung lymph flow from 1.3 to 5.0 ml/15 min and an increase in lymph-to-plsma protein concentration ratios. Reperfusion, but not ischemia alone, caused an increase in wet-to-dry weight ratios in both the reperfused left lung and the contralateral right lung. Granulocytes increased in both lungs during the ischemic period and after reperfusion, and hypoxemia developed after reperfusion. The calcium channel antagonist, verapamil, given just before reperfusion, caused a marked attenuation in the reperfusion-induced changes in the lung lymph variables and wet-to-dry weight ratio. However, verapamil did not affect the hypoxemia or granulocyte sequestration seen after reperfusion. We conclude that reperfusion of ischemic sheep lung results in increased microvascular permeability that can be partially prevented by verapamil.     

Progranulin protects against cerebral ischemia-reperfusion (I/R) injury by inhibiting necroptosis and oxidative stress

Ischemic stroke is a leading cause of mortality and disability worldwide. Nevertheless, its molecular mechanisms have not yet been adequately illustrated. Progranulin (PGRN) is a secreted glycoprotein with pleiotropic functions. In the present study, we found that PGRN expression was markedly reduced in mice after stroke onset through middle cerebral artery occlusion (MCAO). We also showed that necroptosis was a mechanism underlying cerebral I/R injury. Importantly, PGRN knockdown in vivo significantly promoted the infarction volume and neurological deficits scores in mice after MCAO surgery. Necroptosis induced by MCAO was further accelerated by PGRN knockdown, as evidenced by the promoted expression of phosphorylated receptor-interacting protein (RIP) 1 kinase (RIPK1), RIPK3 and mixed lineage kinase domain-like (MLKL), which was accompanied with increased expression of cleaved Caspase-8 and Caspase-3. However, PGRN over-expression was neuroprotective. Additionally, PGRN-regulated ischemic stroke was related to ROS accumulation that MCAO-mice with PGRN knockdown exhibited severe oxidative stress, as proved by the aggravated malondialdehyde (MDA) and lipid peroxidation (LPO) contents, and the decreased superoxide dismutase (SOD) activity. However, PGRN over-expression in mice with cerebral ischemia showed anti-oxidative effects. Finally, PGRN was found to attenuate oxidative damage partly via its regulatory effects on necroptosis. Therefore, promoting PGRN expression could reduced cerebral I/R-induced brain injury by suppressing neroptosis and associated reactive oxygen species (ROS) production. These data elucidated that PGRN might provide an effective therapeutic treatment for ischemic stroke.     

Gypenosides alleviate myocardial ischemia-reperfusion injury via attenuation of oxidative stress and preservation of mitochondrial function in rat heart

Gypenosides (GP) are the predominant components of Gynostemma pentaphyllum, a Chinese herb medicine that has been widely used for the treatment of chronic inflammation, hyperlipidemia, and cardiovascular disease. GP has been demonstrated to exert protective effects on the liver and brain against ischemia-reperfusion (I/R) injury, yet whether it is beneficial to the heart during myocardial I/R is unclear. In this study, we demonstrate that pre-treatment with GP dose-dependently limits infarct size, alleviates I/R-induced pathological changes in the myocardium, and preserves left ventricular function in a rat model of cardiac I/R injury. In addition, GP pre-treatment reduces oxidative stress and protects the intracellular antioxidant machinery in the myocardium. Further, we show that the cardioprotective effect of GP is associated with the preservation of mitochondrial function in the cardiomyocytes, as indicated by ATP level, enzymatic activities of complex I, II, and IV on the mitochondrial respiration chain, and the activity of citrate synthase in the citric acid cycle for energy generation. Moreover, GP maintains mitochondrial membrane integrity and inhibits the release of cytochrome c from the mitochondria to the cytosol. The cytoprotective effect of GP is further confirmed in vitro in H9c2 cardiomyoblast cell line with oxygen-glucose deprivation and reperfusion (OGD/R), and the results indicate that GP protects cell viability, reduces oxidative stress, and preserves mitochondrial function. In conclusion, our study suggests that GP may be of clinical value in cytoprotection during acute myocardial infarction and reperfusion.     

Protective effect of hyperoside against renal ischemia-reperfusion injury via modulating mitochondrial fission,oxidative stress,and apoptosis

Ischemia/reperfusion (IR) is a common cause of acute kidney injury (AKI). However, effective therapies for IR-induced AKI are lacking. Hyperoside is an active constituent in the flowers of Abelmoschus manihot (L.) Medic, which is a traditional Chinese herbal medicine for the treatment of various ischemic brain and heart diseases. Our previous study demonstrated that hyperoside inhibited adriamycin induced podocyte injury both in vivo and in vitro. The aim of this study is to investigate the effect of hyperoside in IR-induced AKI. In mice, pretreatment of hyperoside could markedly attenuate IR-induced AKI, tubular cell apoptosis, and oxidative stress in the kidneys. Meanwhile, we found hyperoside inhibited IR-induced mitochondrial fission by suppressing OMA1 mediated proteolysis of optic atrophy 1 (OPA1). Consistently, in human proximal tubular epithelial cells, hyperoside might inhibit CoCl₂-induced mitochondrial fission, oxidative stress, and apoptosis by regulating OMA1-OPA1 axis. Taken together, our results support the idea that OMA1-OPA1 mediated mitochondrial fission can be used for the prevention of AKI. Hyperoside might have novel therapeutic potential in the treatment of AKI.     

Albumin Cys34 adducted by acrolein as a marker of oxidative stress in ischemia-reperfusion injury during hepatectomy

The aim of this study was to measure and identify the reactive carbonyl species (RCSs) released in the blood of humans subjected to hepatic resection. Pre-anesthesia malondialdehyde (MDA) plasma content (0.36?±?0.11?nmol/mg protein) remained almost unchanged immediately after anaesthesia, before clamping and at the 10th min after ischemia, while markedly increased (to 0.59?±?0.07?nmol/mg; p?<?0.01, Tukey’s post test) at the 10th min of reperfusion. A similar trend was observed for the protein carbonyls (PCs), whose pre-anesthesia levels (0.17?±?0.13?nmol/mg) did not significantly change during ischemia, while increased more than fourfold at the 10th min of reperfusion (0.75?±?0.17?nmol/mg; p?<?0.01, Tukey’s post test). RCSs were then identified as covalent adducts to the albumin Cys34, which we previously found as the most reactive protein nucleophilic site in plasma. By using a mass spectrometry (MS) approach based on precursor ion scanning, we found that acrolein (ACR) is the main RCS adducted to albumin Cys34. In basal conditions, the adducted albumin was 0.6?±?0.4% of the native form but it increased by almost fourfold at the 10th min of reperfusion (2.3?±?0.7%; p?<?0.01, t-test analysis). Since RCSs are damaging molecules, we propose that RCSs, and ACR in particular, are new targets for novel molecular treatments aimed at reducing the ischemia/reperfusion damage by the use of RCS sequestering agents.     

Favorable balance of anti-oxidant/pro-oxidant systems and ablated oxidative stress in Brown Norway rats in renal ischemia-reperfusion injury

Oxidative stress is important in the pathogenesis of renal ischemia-reperfusion (IR) injury; however whether imbalances in reactive oxygen production and disposal account for susceptibility to injury is unclear. The purpose of this study was to compare necrosis, apoptosis, and oxidative stress in IR-resistant Brown Norway rats vs. IR-susceptible Sprague-Dawley (SD) rats in an in vivo model of renal IR injury. As superoxide (O₂^·−) interacts with nitric oxide (NO) to form peroxynitrite, inducible NO synthase (iNOS) and nitrotyrosine were also examined. Renal IR was induced in SD and BN rats by bilateral clamping of renal arteries for 45 min followed by reperfusion for 24 h (SD 24 and BN 24, respectively). BN rats were resistant to renal IR injury as evidenced by lower plasma creatinine and decreased acute tubular necrosis. TUNEL staining analysis demonstrated significantly decreased apoptosis in the BN rats vs. SD rats after IR. Following IR, O₂^·− levels were also significantly lower in renal tissue of BN rats vs. SD rats (P < 0.05) in conjunction with a preservation of the O₂^·− dismutating protein, CuZn superoxide dismutase (CuZn SOD) (P < 0.05). This was accompanied by an overall decrease in 4-hydroxynonenal adducts in the BN but not SD rats after IR. BN rats also displayed lower iNOS expression (P < 0.05) resulting in lower tissue NO levels and decreased nitrotyrosine formation (P < 0.01) following IR. Collectively these results show that the resistance of the BN rat to renal IR injury is associated with a favorable balance of oxidant production vs. oxidant removal. This work was supported in part by a Medical College of Wisconsin-Research Affairs Committee Grant to V. Nilakantan, and by divisional funds to V. Nilakantan and B.D. Shames.     

Alteration of renal functional, oxidative stress and inflammatory indices following hepatic ischemia-reperfusion

Liver ischemia/reperfusion (IR) injury is a complex phenomenon that may cause local as well as remote organ injuries. Reactive oxygen species (ROS) along with many pro- and anti- inflammatory cytokines are implicated in the development of organ injury. The renal functional, histological, oxidative stress and inflammatory indices were studied during a short and a longer period of liver IR. Rats were subjected to either sham operation or 90 min partial liver ischemia followed by 4 or 24 h of reperfusion. Serum ALT, AST, ALK and LDH levels, BUN and creatinine, renal MDA level, SOD and catalase activities were evaluated as well as serum IL-6 and IL-10 concentrations along with renal histological evaluation. Ninety minutes liver ischemia /4 h reperfusion caused an increase in BUN and renal MDA levels and a decrease in SOD and catalase activities. It also caused an increase in serum IL-6 and IL-10 levels. 24 h liver reperfusion resulted in a reduction in BUN levels and lower oxidative damages demonstrated by a decrease in renal MDA levels and an increase in renal SOD and catalase activities comparing to 4 h reperfusion group. Evaluations indicated improvement in histology such as less cytoplasmic vacuolation and lower tubular debris. Serum inflammatory indices (IL-6 and IL-10 levels) were also reduced. This study showed that liver IR damage causes renal injury including functional, inflammatory and oxidative status changes. The remote kidney damage was then improved by continuing reperfusion from 4 to 24 h.     

内质网应激预处理条件下大鼠肝脏缺血再灌注损伤模型的建立

目的:通过建立了内质网应激预处理条件下的大鼠肝脏缺血再灌注损伤模型,探讨内质网应激预处理在体内的应用.方法:以衣霉素为内质网应激诱导剂,采用大鼠肝脏70%缺血再灌注损伤模型.按照不同给药剂量分为50μ g/kg组、100μ g,kg组、200μ g/kg组、对照组,观察不同给药剂量条件下,血清转氨酶水平的变化.结果:给药100μ g/kg体重、诱导5天条件下大鼠术后转氨酶水平显著低于对照组.其它组与对照组无统计学差异.肝组织病理切片证实该预处理条件对肝脏缺血再灌注损伤有显著保护作用.结论:在特定的给药剂量条件下,衣霉素诱导的内质网应激预处理对大鼠肝脏缺血再灌注损伤有显著的保护作用.     

Protection against ischemia-reperfusion induced oxidative stress by vitamin E treatment.

The rat heart protection offered by vitamin E against oxidative stress after ischaemia-reperfusion was studied by using a new methodological approach. Functional recovery of hearts from ischaemia-reperfusion was correlated with a traditional index of oxidative stress such as lipid peroxidation and with antioxidant capacity and susceptibility to oxidants of the tissue evaluated by enhanced chemiluminescence techniques. Rats were treated with ten daily i.m. injections of 100 mg/kg body weight of vitamin E. The functional recovery during reperfusion (20 min, following 45 min ischaemia) of Langendorff preparations from control (vehicle-injected) and vitamin E treated rats was evaluated in terms of heart rate, left ventricular developed pressure (LVDP), double product (= heart rate. LVDP) and coronary flow recovery. Vitamin E treatment significantly improved functional recovery of heart rate, LVDP, double product and coronary flow. It also increased the level of vitamin E and reduced the levels of both malondialdehyde and hydroperoxides in the heart tissue at the end of the ischaemia-reperfusion protocol. In contrast, it did not affect the antioxidant capacity and the response of heart homogenates to in vitro oxidative stress measured after ischaemia-reperfusion. These results show a protective action of vitamin E treatment against lipid peroxidation and cardiac dysfunction associated with ischaemia-reperfusion. Although the precise mechanism of this protection is not evident, our model in part suggests a role of vitamin E other than as a free radical scavenger.     

Retraction statement: The protective effects of propofol against renal ischemia-reperfusion injury are potentiated by norisoboldine treatment via inhibition of oxidative stress pathways

The following article, published online on 31 October 2021 in Wiley Online Library ( wileyonlinelibrary.com ), has been retracted by agreement between the authors, the journal Editor in Chief, Hari Bhat, and Wiley Periodicals, LLC. Following publication, concerns were raised by authors regarding Figure 2. The retraction has been agreed because of concerns that the figures were duplicated and/or manipulated, affecting the interpretation of the data and results presented.     

Arachidonic acid cytotoxicity in leukocytes: implications of oxidative stress and eicosanoid synthesis

Arachidonic acid (AA)-induced cytotoxicity was evaluated in leukocytes: the human leukemia cell lines HL-60, Jurkat and Raji and in rat lymphocytes. Such cytotoxicity was dose- and time-dependent. At concentrations below 5 microM, AA was not toxic; at 10-400 microM, AA induced apoptosis and at concentrations beyond 400 microM, necrosis. The minimum exposure time to trigger cell death was of around 1 h, but the effect was increased by longer exposure times until 6-24 h. Apoptosis was morphologically characterized by a decrease in cell and nuclear volume, chromatin condensation and DNA fragmentation and the presence of lipid bodies, without changes in organelle integrity. Biochemically, AA-induced apoptosis was associated with internucleosomal fragmentation and caspase activation, evaluated by PARP cleavage and the use of a caspase inhibitor. Necrosis was characterized by increased cell volume, presence of loose chromatin, appearance of vacuoles, loss of membrane integrity and of the definition of organelles. The apoptotic effect of AA was studied as to oxidative-reductive imbalance and the participation of eicosanoids. Apoptotic AA treatment was accompanied by an increase in the quantity of thiobarbituric acid reactive substances (TBARS), low-level chemiluminescence and in the glutathione disulfide/reduced glutathione ratio, indicating oxidative stress. The addition of tocopherol, ascorbate, prostaglandin E2 and lipoxygenase inhibitors delayed cell death, whereas the inhibition of cyclooxygenase promoted AA-induced cell death. Cell treatment with AA was accompanied by increased cellular production of LTB4. AA, therefore, is cytotoxic at physiological and supraphysiological concentrations, causing apoptosis and necrosis. Cell treatment with apoptotic concentrations of AA involves oxidative stress and changes in eicosanoid biosynthesis.     

Targeting oxidative stress response by green tea polyphenols: clinical implications

Abstract

Green tea polyphenols, the most interesting constituent of green tea leaves, have been shown to have both pro-oxidant and antioxidant properties. Both pro-oxidant and antioxidant properties are expected to contribute to modulation of oxidative stress response under ideal optimal dosage regimens. Exposure to a low concentration of a pro-oxidant prior to exposure to oxidative stress induces the expression of genes that code for proteins that induce adaptation in a subsequent oxidative stress. On the other hand, exposure to an antioxidant concurrently with exposure to the oxidative stress affords protection through free radical scavenging or through other indirect antioxidant mechanisms. In any case, the optimal conditions that afford protection from oxidative stress should be defined for any substance with redox properties. Green tea polyphenols, being naturally occurring substances, seem to be an ideal option for the modulation of oxidative stress response. This paper reviews available data on the pro-oxidant and antioxidant properties of green tea polyphenols focusing on their potential on the modulation of oxidative stress response.     

Interaction between mitochondria and oxidative stress in neuronal injury

Mitochondria may be both the source and the target of oxidative stress in neurodegenerative disease. In models of excitotoxicity, neuronal injury is triggered by the influx of calcium into neurons and then into mitochondria. Our studies suggest that an important consequence of this calcium movement is the generation of ROS by mitochondria. Studies with isolated mitochondria suggest that calcium may enhance ROS generation by mitochondria, especially when complex I is impaired. However, these studies are complicated by a lack of specificity of detection methods like Amplex Red. One feature of mitochondria is their movement within neurons. We used fluorescent proteins targeted to mitochondria to follow trafficking in neurons. Neurotoxins like glutamate, zinc and peroxide, which feature oxidative stress in their mechanism of action, affect mitochondrial movement, morphology or both. We speculate that restricting the delivery of mitochondria to their targets within neurons could impair neuronal viability.     

New strategy of bone marrow mesenchymal stem cells against oxidative stress injury via Nrf2 pathway: oxidative stress preconditioning

Clinically, bone marrow mesenchymal stem cells (BMSCs) have been used in treatment of many diseases, but the local oxidative stress (OS) of lesion severely limits the survival of BMSCs, which reduces the efficacy of BMSCs transplantation. Therefore, enhancing the anti-OS stress ability of BMSCs is a key breakthrough point. Preconditioning is a common protective mechanism for cells or body. Here, the aim of this study was to investigate the effects of OS preconditioning on the anti-OS ability of BMSCs and its mechanism. Fortunately, OS preconditioning can increase the expression of superoxide dismutase, catalase, NQO1, and heme oxygenase 1 through the nuclear factor erythroid 2-related factor 2 pathway, thereby decreased the intracellular reactive oxygen species (ROS) levels, relieved the damage of ROS to mitochondria, DNA and cell membrane, enhanced the anti-OS ability of BMSCs, and promoted the survival of BMSCs under OS.     

Proteasome inhibition in oxidative stress neurotoxicity: implications for heat shock proteins

Recent studies have demonstrated that inhibition of the proteasome, an enzyme responsible for the majority of intracellular proteolysis, may contribute to the toxicity associated with oxidative stress. In the present study we demonstrate that exposure to oxidative injury (paraquat, H(2)O(2), FeSO(4)) induces a rapid increase in reactive oxygen species (ROS), loss of mitochondrial membrane potential, inhibition of proteasome activity, and induction of cell death in neural SH-SY5Y cells. Application of proteasome inhibitors (MG115, epoxomycin) mimicked the effects of oxidative stressors on mitochondrial membrane potential and cell viability, and increased vulnerability to oxidative injury. Neural SH-SY5Y cells stably transfected with human HDJ-1, a member of the heat shock protein family, were more resistant to the cytotoxicity associated with oxidative stressors. Cells expressing increased levels of HDJ-1 displayed similar degrees of ROS formation following oxidative stressors, but demonstrated a greater preservation of mitochondrial function and proteasomal activity following oxidative injury. Cells transfected with HDJ-1 were also more resistant to the toxicity associated with proteasome inhibitor application. These data support a possible role for proteasome inhibition in the toxicity of oxidative stress, and suggest heat shock proteins may confer resistance to oxidative stress, by preserving proteasome function and attenuating the toxicity of proteasome inhibition.