Ischemia-reperfusion Injury Damage Research Articles

SAT-138 ROLE OF GUT COMMENSAL BACTERIA IN ISCHEMIA/REPERFUSION INDUCED ACUTE KIDNEY INJURY

Emerging evidence suggests the critical role of gut commensal bacteria in health and diseases by modulating local and systemic immune response. However, the role of the microbiome and gut-derived immunity in the development of kidney ischemia/reperfusion injury (IRI) is largely unknown. The purpose of this study is to examine the role of the gut microbiome and mucosal immunity in the development of kidney IRI and distant organ damage. C57BL/6 mice were fed with a combination of oral antibiotics (neomycin, ampicillin, metronidazole and vancomycin) or vehicle for 2 weeks and then underwent bilateral renal pedicle clamping. Renal function, histological kidney injury, gut permeability, gut-derived local and systemic immune response as well as microbiome analyses were performed. IRI induced renal functional, histological deterioration was accompanied by alteration of the gut microbiome. Kidney IRI resulted in a significant decrease in the diversity index of the microbiome, as well as the number of operational taxonomic units (OTUs). Among them, the reduction of short-chain fatty acid producing species such as Ruminococcaceae, Bacteroides, Christensenellaae, Lachnospiraceae was prominent. Altered microbiome after IRI was associated with the development of “leaky gut” and colitis that were associated with increased number of colon epithelial cell apoptosis, neutrophil and M1 macrophage infiltration in the colon. Gut microbiota depletion by oral antibiotic treatment but not by systemic antibiotics significantly attenuated kidney injury, as well as distant organ damage. The renoprotective effect of oral antibiotic treatment was associated with partial restoration of “leaky gut” with preserved tight junction proteins, decreased number of colon epithelial cell apoptosis or neutrophil or M1 macrophage-mediated colitis. This protective effect was also associated with a reduction of systemic proinflammatory cytokines and increase of anti-inflammatory cytokine IL-10. More importantly, alteration of the gut microbiome in oral antibiotics fed mice was associated significantly increased number of CD4+ CD25+ Tregs and Foxp3 expression in cervical lymph node and spleen following IRI. Our data showed the critical role of the commensal gut microbiome in the development of kidney IRI injury as well as distant organ injury. Antibiotic modification of gut microbiome induced renoprotective effect is thought to be partially mediated by modulating peripheral and systemic immune response toward Treg mediated immune tolerance. Targeting the gut might offer a new paradigm in the prevention of treatment of AKI.

Sodium butyrate relieves cerebral ischemia-reperfusion injury in mice by inhibiting JNK/STAT pathway.

The aim of this study was to investigate whether sodium butyrate (NaB) attenuated cerebral ischemia-reperfusion injury (IRI) in mice by inhibiting JNK/STAT pathway, thereby exerting a neuroprotective role. ICR mice were randomly assigned into five groups, including the sham group, the model group, the 1 mg/kg NaB group, the 5 mg/kg NaB group and the 10 mg/kg NaB group, respectively. IRI model was established in mice using the bilateral common carotid artery occlusion (BCCAO) method. Open-field test was performed to evaluate degree of IRI damage by recording central travel distance and central active time. The morphology of hippocampal neurons was observed by hematoxylin and eosin (HE) staining. TUNEL staining was conducted to detect apoptotic neurons in the brain of mice. Meanwhile, activities of superoxide dismutase (SOD) and malondialdehyde (MDA) in brain tissues of mice were determined by relative commercial kits. The expression levels of inflammatory factors in brain tissues of mice were accessed using enzyme-linked immunosorbent assay (ELISA). In addition, the protein expressions of Jak2 and STAT3 in brain tissues of mice were detected by Western blot. 10 mg/kg NaB treatment remarkably alleviated impaired neurological defect and hippocampal neurons, as well as significantly improved neuronal survival. Mice in the 10 mg/kg NaB group showed significantly lower central travel distance and shorter central active time than those in the sham group. In addition, 10 mg/kg NaB treatment markedly increased SOD activity, whereas significantly decreased MDA activity in IRI mice. Mice in the NaB treatment group showed significantly lower levels of IL-1β, TNF-α and IL-8. Meanwhile, TUNEL-positive neurons in mice of the NaB treatment group were remarkably fewer. In addition, the protein expression levels of Jak2 and STAT3 were obviously upregulated in IRI mice, which were significantly downregulated after 10 mg/kg NaB treatment. Sodium butyrate exerts neuroprotective effects on cerebral ischemia-reperfusion injury by preventing oxidative stress, inflammatory response and neuronal apoptosis through inhibiting JNK/STAT pathway.

Ubiquitin-proteasome system and oxidative stress in liver transplantation

A major issue in organ transplantation is the development of a protocol that can preserve organs under optimal conditions. Damage to organs is commonly a consequence of flow deprivation and oxygen starvation following the restoration of blood flow and reoxygenation. This is known as ischemia-reperfusion injury (IRI): a complex multifactorial process that causes cell damage. While the oxygen deprivation due to ischemia depletes cell energy, subsequent tissue oxygenation due to reperfusion induces many cascades, from reactive oxygen species production to apoptosis initiation. Autophagy has also been identified in the pathogenesis of IRI, although such alterations and their subsequent functional significance are controversial. Moreover, proteasome activation may be a relevant pathophysiological mechanism. Different strategies have been adopted to limit IRI damage, including the supplementation of commercial preservation media with pharmacological agents or additives. In this review, we focus on novel strategies related to the ubiquitin proteasome system and oxidative stress inhibition, which have been used to minimize damage in liver transplantation.

22-oxacalcitriol prevents acute kidney injury via inhibition of apoptosis and enhancement of autophagy.

The pathophysiology of ischemic acute kidney injury (AKI) is thought to include a complex interplay between tubular cell damage and regeneration. Several lines of evidences suggest a potential renoprotective effect of vitamin D. In this study, we investigated the effect of 22-oxacalcitriol (OCT), a synthetic vitamin D analogue, on renal fate in a rat model of ischemia reperfusion injury (IRI) induced acute kidney injury (AKI). 22-oxacalcitriol (OCT) was administered via intraperitoneal (IP) injection before ischemia, and continued after IRI that was performed through bilateral clamping of the renal pedicles. 96h after reperfusion, rats were sacrificed for the evaluation of autophagy, apoptosis, and cell cycle arrest. Additionally, assessments of toll-like receptors (TLR), interferon gamma (IFN-g) and sodium-hydrogen exchanger-1 (NHE-1) were also performed to examine their relations to OCT-mediated cell response. Treatment with OCT-attenuated functional deterioration and histological damage in IRI induced AKI, and significantly decreased cell apoptosis and fibrosis. In comparison with IRI rats, OCT + IRI rats manifested a significant exacerbation of autophagy as well as reduced cell cycle arrest. Moreover, the administration of OCT decreased IRI-induced upregulation of TLR4, IFN-g and NHE-1. These results demonstrate that treatment with OCT has a renoprotective effect in ischemic AKI, possibly by suppressing cell loss. Changes in the expression of IFN-g and NHE-1 could partially link OCT to the cell survival-promoted effects.

Quantitative Evaluation of Hepatic Microvascular Perfusion after Ischemia–Reperfusion Injury in Rabbits by Contrast-Enhanced Ultrasound Perfusion Imaging

The aim of this study was to evaluate microvascular perfusion after liver ischemia–reperfusion injury (IRI) in rabbits using the “flash-replenishment” method of contrast-enhanced ultrasound (CEUS) perfusion imaging. Twenty-eight rabbits underwent either 30, 60 or 90 min of ischemia and 120 min of reperfusion. CEUS perfusion imaging was performed using the “flash-replenishment” model, and hepatic microvascular perfusion parameters, including peak intensity (PI), area under the curve (AUC), and hepatic artery-to-vein transit time (HA-HVTT), were calculated. Prolonged ischemia upregulated intracellular adhesion molecule-1 (ICAM-1), alanine transaminase (ALT) and aspartate transaminase (AST) levels. Longer ischemia decreased PI and AUC, but increased HA-HVTT. The perfusion parameters were significantly correlated with Suzuki's pathology scores and ALT and AST levels. The “flash-replenishment” method of CEUS perfusion imaging is an accurate and non-invasive method for evaluating hepatic microvascular perfusion and provides a valuable experimental basis for early prediction of liver IRI damage after liver transplantation or liver resection.

Free Radical Damage in Ischemia-Reperfusion Injury: An Obstacle in Acute Ischemic Stroke after Revascularization Therapy.

Acute ischemic stroke is a common cause of morbidity and mortality worldwide. Thrombolysis with recombinant tissue plasminogen activator and endovascular thrombectomy are the main revascularization therapies for acute ischemic stroke. However, ischemia-reperfusion injury after revascularization therapy can result in worsening outcomes. Among all possible pathological mechanisms of ischemia-reperfusion injury, free radical damage (mainly oxidative/nitrosative stress injury) has been found to play a key role in the process. Free radicals lead to protein dysfunction, DNA damage, and lipid peroxidation, resulting in cell death. Additionally, free radical damage has a strong connection with inducing hemorrhagic transformation and cerebral edema, which are the major complications of revascularization therapy, and mainly influencing neurological outcomes due to the disruption of the blood-brain barrier. In order to get a better clinical prognosis, more and more studies focus on the pharmaceutical and nonpharmaceutical neuroprotective therapies against free radical damage. This review discusses the pathological mechanisms of free radicals in ischemia-reperfusion injury and adjunctive neuroprotective therapies combined with revascularization therapy against free radical damage.

Cytoprotective activated protein C averts Nlrp3 inflammasome–induced ischemia-reperfusion injury via mTORC1 inhibition

AbstractCytoprotection by activated protein C (aPC) after ischemia-reperfusion injury (IRI) is associated with apoptosis inhibition. However, IRI is hallmarked by inflammation, and hence, cell-death forms disjunct from immunologically silent apoptosis are, in theory, more likely to be relevant. Because pyroptosis (ie, cell death resulting from inflammasome activation) is typically observed in IRI, we speculated that aPC ameliorates IRI by inhibiting inflammasome activation. Here we analyzed the impact of aPC on inflammasome activity in myocardial and renal IRIs. aPC treatment before or after myocardial IRI reduced infarct size and Nlrp3 inflammasome activation in mice. Kinetic in vivo analyses revealed that Nlrp3 inflammasome activation preceded myocardial injury and apoptosis, corroborating a pathogenic role of the Nlrp3 inflammasome. The constitutively active Nlrp3A350V mutation abolished the protective effect of aPC, demonstrating that Nlrp3 suppression is required for aPC-mediated protection from IRI. In vitro aPC inhibited inflammasome activation in macrophages, cardiomyocytes, and cardiac fibroblasts via proteinase-activated receptor 1 (PAR-1) and mammalian target of rapamycin complex 1 (mTORC1) signaling. Accordingly, inhibiting PAR-1 signaling, but not the anticoagulant properties of aPC, abolished the ability of aPC to restrict Nlrp3 inflammasome activity and tissue damage in myocardial IRI. Targeting biased PAR-1 signaling via parmodulin-2 restricted mTORC1 and Nlrp3 inflammasome activation and limited myocardial IRI as efficiently as aPC. The relevance of aPC-mediated Nlrp3 inflammasome suppression after IRI was corroborated in renal IRI, where the tissue protective effect of aPC was likewise dependent on Nlrp3 inflammasome suppression. These studies reveal that aPC protects from IRI by restricting mTORC1-dependent inflammasome activation and that mimicking biased aPC PAR-1 signaling using parmodulins may be a feasible therapeutic approach to combat IRI.

Neutrophil extracellular traps in acrolein promoted hepatic ischemia reperfusion injury: Therapeutic potential of NOX2 and p38MAPK inhibitors.

Neutrophil is a significant contributor to ischemia reperfusion (IR) induced liver tissue damage. However, the exact role of neutrophils in IR induced innate immune activation and liver damage is not quite clear. Our study sheds light on the role of chronic oxidative stress end products in worsening the IR inflammatory process by neutrophil recruitment and activation following liver surgery. We employed specific inhibitors for molecular targets-NOX2 (NADPH oxidase 2) and P38 MAPK (Mitogen activated protein kinase) signal to counteract neutrophil activation and neutrophil extracellular trap (NET) release induced liver damage in IR injury. We found that acrolein initiated neutrophil chemotaxis and induced NET release both in vitro and in vivo. Acrolein exposure caused NET induced nuclear and mitochondrial damage in HepG2 cells as well as aggravated the IR injury in rat liver. Pretreatment with F-apocynin and naringin, efficiently suppressed acrolein induced NET release in vitro. Notably, it suppressed the expression of inflammatory cytokines, P38MAPK-ERK activation, and apoptotic signals in rat liver exposed to acrolein and subjected to IR. Moreover, this combination effectively attenuated acrolein induced NET release and hepatic IR injury. In the current study we have shown that the acrolein accumulation in liver due to chronic stress, is responsible for neutrophil recruitment and its activation leading to NET induced liver damage during surgery. Our study shows that therapeutic targeting of NOX2 and P38MAPK signaling in patients with chronic hepatic disorders would improve post operative hepatic function and survival.

Overexpression of Human CD55 and CD59 or Treatment with Human CD55 Protects against Renal Ischemia-Reperfusion Injury in Mice.

Deficiency in the membrane-bound complement regulators CD55 and CD59 exacerbates renal ischemia-reperfusion injury (IRI) in mouse models, but the effect of increasing CD55 and CD59 activity has not been examined. In this study, we investigated the impact of overexpression of human (h) CD55 ± hCD59 or treatment with soluble rhCD55 in a mouse model of renal IRI. Unilaterally nephrectomised mice were subjected to 18 (mild IRI) or 22 min (moderate IRI) warm renal ischemia, and analyzed 24 h after reperfusion for renal function (serum creatinine and urea), complement deposition (C3b/c and C9), and infiltration of neutrophils and macrophages. Transgenic mice expressing hCD55 alone were protected against mild renal IRI, with reduced creatinine and urea levels compared with wild type littermates. However, the renal function of the hCD55 mice was not preserved in the moderate IRI model, despite a reduction in C3b/c and C9 deposition and innate cell infiltration. Mice expressing both hCD55 and hCD59, on the other hand, were protected in the moderate IRI model, with significant reductions in all parameters measured. Wild type mice treated with rhCD55 immediately after reperfusion were also protected in the moderate IRI model. Thus, manipulation of CD55 activity to increase inhibition of the C3 and C5 convertases is protective against renal IRI, and the additional expression of hCD59, which regulates the terminal complement pathway, provides further protection. Therefore, anti-complement therapy using complement regulatory proteins may provide a potential clinical option for preventing tissue and organ damage in renal IRI.

C5aR2 Deficiency Improves Renal Regeneration after Renal Ischemia Reperfusion Injury and in Kidney Transplantation in Mice

ObjectiveThe complement receptors C5aR1 and C5aR2 serve distinct roles in immune regulation. In kidney transplantation ischemia reperfusion injury (IRI) results in rapid complement activation. In this study C5aR1 and C5aR2 deficient mice were tested in a model of renal ischemia reperfusion injury (IRI) and in an isogenic cross over kidney transplantation (ktx) model.MethodsIRI was induced by unilateral clipping of renal pedicle for 45 min in C5aR1, C5aR2 −/− and wild type mice (WT). Renal morphology, inflammation, peritubular capillary density and renal fibrosis were investigated by immunohistochemistry. FACS analysis was done at d7 after IRI to analyze infiltrating subsets of myeloid and lymphocytes. To study renal perfusion impairment due to IRI arterial spin labelling was done. In a second model isogenic ktx with prolonged cold ischemia time of 90 min was performed and C5aR1−/−, C5aR2−/− or WT mice served as donors or recipients.ResultsWT mice showed dramatic decrease of renal perfusion and severe inflammation resulting in interstitial fibrosis at three weeks after IRI with substantial loss of kidney volume. C5aR2 −/− mice had less inflammation and started to regenerate at 7 days after IRI. Renal fibrosis was attenuated in C5aR2−/− mice which had less rarefication of peritubular capillaries compared to WT IRI kidneys. In the ktx model C5aR2 −/− of the recipient showed the best renal morphology with attenuated renal ischemia reperfusion injury of the graft. By FACS analysis differential activation in γδ‐Tcells in C5aR2 deficient mice was observed and may have contributed to enhanced regeneration.ConclusionC5aR2 deficiency attenuates renal damage and fibrosis in renal IRI and ktx by better regeneration and protection of capillary integrity of the renal tissue.

MicroRNA-155 aggravates ischemia-reperfusion injury by modulation of inflammatory cell recruitment and the respiratory oxidative burst.

The inflammatory sequelae of ischemia-reperfusion injury (IRI) are a major causal factor of tissue injury in various clinical settings. MicroRNAs (miRs) are short, non-coding RNAs, which regulate protein expression. Here, we investigated the role of miR-155 in IR-related tissue injury. Quantifying microRNA-expression levels in a human muscle tissue after IRI, we found miR-155 expression to be significantly increased and to correlate with the increased expression of TNF-α, IL-1β, CD105, and Caspase3 as well as with leukocyte infiltration. The direct miR-155 target gene SOCS-1 was downregulated. In a mouse model of myocardial infarction, temporary LAD ligation and reperfusion injury resulted in a smaller area of necrosis in miR-155-/- animals compared to wildtype animals. To investigate the underlying mechanisms, we evaluated the effect of miR-155 on inflammatory cell recruitment by intravital microscopy and on the generation of reactive oxygen species (ROS) of macrophages. Our intravital imaging results demonstrated a decreased recruitment of inflammatory cells in miR-155-/- animals during IRI. The generation of ROS in leukocytic cells of miR-155-/- animals was also reduced. RNA silencing of the direct miR-155 target gene SOCS-1 abrogated this effect. In conclusion, miR-155 aggravates the inflammatory response, leukocyte infiltration and tissue damage in IRI via modulation of SOCS-1-dependent generation of ROS. MiR-155 is thus a potential target for the treatment or prevention of IRI.

Vitamin D deficiency aggravates ischemic acute kidney injury in rats.

Vitamin D deficiency (VDD) increases the risk of death in hospitalized patients. Renal ischemia/reperfusion injury (IRI) induces acute kidney injury (AKI), which activates cell cycle inhibitors, including p21, a cyclin-dependent kinase inhibitor and genomic target of 25-hydroxyvitamin D, which is in turn a potent immunomodulator with antiproliferative effects. In this study, we assess the impact of VDD in renal IRI. Wistar rats were divided into groups, each evaluated for 30 days: control (receiving a standard diet); VDD (receiving a vitamin D-free diet); IRI (receiving a standard diet and subjected to 45-min bilateral renal ischemia on day 28); and VDD + IRI (receiving a vitamin D-free diet and subjected to 45-min bilateral renal ischemia on day 28). At 48 h after IRI, animals were euthanized; blood, urine, and kidney tissue samples were collected. Compared with IRI rats, VDD + IRI rats showed a more severe decrease in glomerular filtration rate, greater urinary protein excretion, a higher kidney/body weight ratio and lower renal aquaporin 2 expression, as well as greater morphological damage, characterized by increased interstitial area and tubular necrosis. Our results suggest that the severity of tubular damage in IRI may be associated with downregulation of vitamin D receptors and p21. VDD increases renal inflammation, cell proliferation and cell injury in ischemic AKI.

Complement cascade and kidney transplantation: The rediscovery of an ancient enemy.

The identification of complement activity in serum and immunohistochemical samples represents a core element of nephropathology. On the basis of this observation, different experimental models and molecular studies have shown the role of this cascade in glomerular disease etiology, but the absence of inhibiting drugs have limited its importance. Since 2006, the availability of target-therapies re-defined this ancient pathway, and its blockage, as the new challenging frontier in renal disease treatment. In the graft, the complement cascade is able to initiate and propagate the damage in ischemia-reperfusion injury, C3 glomerulopathy, acute and chronic rejection, atypical hemolytic uremic syndrome and, probably, in many other conditions. The importance of complement-focused research is revealed by the evidence that eculizumab, the first complement-targeting drug, is now considered a valid option in atypical hemolytic uremic syndrome treatment but it is also under investigation in all the aforementioned conditions. In this review we evaluate the importance of complement cascade in renal transplantation diseases, focusing on available treatments, and we propose a speculative identification of areas where complement inhibition may be a promising strategy.

Sivelestat Sodium Hydrate Inhibits Neutrophil Migration to the Vessel Wall and Suppresses Hepatic Ischemia–Reperfusion Injury

Sivelestat sodium hydrate (sivelestat) is a specific neutrophil elastase inhibitor that is effective in treating acute lung injury associated with systemic inflammatory response syndrome. As such, it may be useful in treating hepatic ischemia-reperfusion injury (IRI), a condition in which neutrophils transmigrate into the interstitium, leading to release of neutrophil elastase from neutrophils and consequent damage to the affected tissue, particularly in cases of hepatic failure after liver transplantation or massive liver resection. The purpose of this study was to examine whether treatment with sivelestat inhibits neutrophil adhesion and migration to the vessel wall and suppresses hepatic IRI. Whether and, if so, the extent to which sivelestat suppresses the adhesion and migration of neutrophils and reduces liver damage in hepatic IRI was examined in a human umbilical vein endothelial cell (HUVEC) model and a rat hepatic IRI model. In the HUVEC model, the extent of the adhesion and migration of neutrophils stimulated by platelet-activating factor were found to be dose-dependently inhibited by sivelestat treatment (p < 0.05). In the rat model, serum liver enzyme levels were significantly lower at 12 h after reperfusion, and the number of neutrophils that had migrated to extravascular sites was significantly less in the treatment group compared to the control group (p < 0.05). Sivelestat inhibits the adhesion and migration of neutrophils to vascular endothelium in hepatic IRI, thereby suppressing liver injury.

Estradiol Worsens the Syndrome of Ischemia-Reperfusion Injury in an Experimental Lung Transplantation Model

Ischemia-reperfusion injury (IRI) is a common complication after lung transplantation. There is evidence that reactive oxygen species are involved in its pathogenesis. We designed an experimental study to evaluate whether the administration of antioxidants to lung transplantation recipients protects against IRI and early acute rejection (AR). Twenty-five rats received left lung transplants after 6h of ischemia. Fifty minutes before the reperfusion, groups of five rats received a single dose of desferrioxamine (20mg/kg), estradiol (25mg/kg), or melatonin (10mg/kg). The animals were killed 48h after surgery and the postoperative outcome, IRI, and AR were evaluated. The frequency of severe injury and of moderate-to-severe edema was higher in animals treated with estradiol than in the control group (P=0.022 and P=0.026, respectively). No significant changes in the degree of IRI or AR were observed in the groups treated with desferrioxamine or melatonin. In our study, treatment with the antioxidants melatonin or desferrioxamine before reperfusion had no effects on IRI damage or on AR frequency or severity. However, treatment with estradiol resulted in a worse postoperative outcome and in severe edema. Therefore, despite the antioxidant capacity of estradiol, it is recommended that an evaluation of these adverse effects of estradiol in human lung transplant recipients be performed.

The effects of lycopene on reactive oxygen species and anoxic damage in ischemia reperfusion injury in rats

To study the protective effects of lycopene (LP) on cerebral ischemia-reperfusion injury induced by focal cerebral ischemia and oxidative stress in rats. 48 male Sprague-Dawley (SD) rats were randomly assigned into five groups: A (20 mg/kg LP), B (5 mg/kg LP), C (salad oil), D (salad oil) and E (basic feed control). A, B and C groups were given LP or salad oil orally for 15 d, then cerebral ischemia-reperfusion injury was established by middle cerebral artery occlusion (MCAO) and D group was used as fake surgery control. The contents of reactive oxygen species (ROS), nitric oxide (NO), lactic acid (LD) and the activities of nitric oxide synthetase (NOS) in cortex were measured at 24 h after reperfusion. The levels of HIF-1alpha mRNA and Bcl-2 mRNA in hippocampi were determined by using reverse transcription polymerase chain reaction (RT- PCR) technique. ROS levels of A, B, C, D and E groups were (114.23 +/- 18.91), (135.89 +/- 14.17), (171.37 +/- 25.76), (94.24 +/- 2.23) and (92.06 +/- 5.59) fluorescence intensity value/g protein, respectively (F = 9.038, P < 0.01); levels of NO were (6.60 +/- 0.77), (7.13 +/- 0.47), (8.38 +/- 0.80), (5.52 +/- 0.16) and (5.23 +/- 0.51) micromol/g protein respectively (F = 10.197, P < 0.01); levels of NOS were (0.817 +/- 0.016), (0.875 +/- 0.095), (1.030 +/- 0.101), (0.557 +/- 0.094) and (0.595 +/- 0.066) U/mg protein respectively (F = 14.555, P < 0.01); levels of LD were (0.381 +/- 0.069), (0.446 +/- 0.012), (0.576 +/- 0.059), (0.359 +/- 0.021) and (0.310 +/- 0.036) mmol/g protein respectively (F = 10.043, P < 0.01); HIF-1alpha mRNA expression levels in hippocampi were 0.865 +/- 0.274, 0.635 +/- 0.069, 0.491 +/- 0.067, 0.375 +/- 0.052 and 0.361 +/- 0.087, respectively (F = 40.520, P < 0.01); and Bcl-2 mRNA expression levels in hippocampi were 0.263 +/- 0.033, 0.330 +/- 0.028, 0.198 +/- 0.034, 0.304 +/- 0.039 and 0.236 +/- 0.025, respectively (F = 11.003, P < 0.01). The protective effects of LP may be related with its abilities of decreasing ROS and LD cumulation, alleviating inflammation and up-regulating the expression of protective genes.

Hypothermic Cardioprotection Attenuates Mitochondrial Permeability Transition Pore Opening and Calcium Loading in Isolated Cardiac Mitochondria

Ischemia-reperfusion injury (IRI) is associated with mitochondrial permeability transition pore (mPTP) opening and impaired mitochondrial respiration. Hypothermia attenuates IRI. We examined mitochondrial function in mitochondria obtained from isolated hearts subjected to warm or cold ischemia. Guinea pig isolated hearts were perfused at constant pressure with Krebs-Ringer's solution at 37°C and subjected to 30 min global ischemia at 37°C or 17°C. After 5 min of reperfusion mitochondria were isolated. Mitochondrial [Ca2+]m, membrane potential (ΔΨm), and NADH were measured by spectrophotometry at appropriate wavelengths with indo-1, BCECF, rhodamine 123 fluorescent dyes, and autofluorescence, respectively. After energizing with pyruvic acid, 0-100 μM CaCl2 (0.03-60 μM free [Ca2+]e) was added followed by 250 μM ADP. Ca2+ -induced mPTP opening was assessed by collapse of ΔΨm. 10 μM [Ca2+]e resulted in mPTP opening after 37°C IRI, but only at 35 μM [Ca2+]e after 17°C IRI. ADP decreased ΔΨm and NADH and increased [Ca2+]m in all mitochondria, but the fall in ΔΨm was greater and the responses to ADP with Ca2+ overloading were worse after 37°C IRI vs. 17°C IRI. The incidence of no state 4 respiration was 25% with no added CaCl2 after 37°C IRI and 0% after 17°C IRI. This study shows that hypothermia prevents IRI damage through pathways restricting mitochondrial Ca2+ loading and preserves mitochondrial redox state and respiration. Moreover, mitochondria protected during ischemia with hypothermia were more resistant to Ca2+-induced mPTP opening and oxidative phosphorylation was better preserved. Hypothermia might prevent conformational changes in the F1F0-ATPsynthase and the ADP/ATP carrier, leading to better mitochondrial function and a resistance to mPTP opening as the ADP/ATP carrier is associated with mPTP opening.

Role of Reactive Oxygen Species in Mediating Hepatic Ischemia-Reperfusion Injury and Its Therapeutic Applications in Liver Transplantation

Increasing evidence has shown that reactive oxygen species (ROS) are important mediators in liver ischemia/reperfusion injury(IRI). ROS include hydrogen peroxide (H 2O 2), superoxide anion (O −2), and hydroxyl radical (HO −), which may be generated by activated Kupffer cells in the liver, contributing to reperfusion injury. Hepatic IRI is a multistep process that damages liver graft function. To establish a series of therapeutic strategies to improve the outcome of liver transplantation, a good understanding of the mechanisms of IRI is essential. However, the detail mechanisms of how ROS lead to hepatocyte damage in IRI remains unclear. The aim of this review was to describe recent developments in the field of oxidative stress research. The first part of this review focused on the key roles and possible mechanisms of ROS in hepatic IRI. The second part of this review summarizes some findings including novel and classic antioxidant methods to ameliorate the hepatocyte damage during IRI.

Oxidant Stress during Simulated Ischemia Primes Cardiomyocytes for Cell Death during Reperfusion

Ischemia-reperfusion injury induces oxidant stress, and the burst of reactive oxygen species (ROS) production after reperfusion of ischemic myocardium is sufficient to induce cell death. Mitochondrial oxidant production may begin during ischemia prior to reperfusion because reducing equivalents accumulate and promote superoxide production. We utilized a ratiometric redox-sensitive protein sensor (heat shock protein 33 fluorescence resonance energy transfer (HSP-FRET)) to assess oxidant stress in cardiomyocytes during simulated ischemia. HSP-FRET consists of the cyan and yellow fluorescent protein fluorophores linked by the cysteine-containing regulatory domain from bacterial HSP-33. During ischemia, ROS-mediated oxidation of HSP-FRET was observed, along with a decrease in cellular reduced glutathione levels. These findings were corroborated by measurements using redox-sensitive green fluorescent protein, another protein thiol ratiometric sensor, which became 93% oxidized by the end of simulated ischemia. However, cell death did not occur during ischemia, indicating that this oxidant stress is not sufficient to induce death before reperfusion. However, interventions that attenuate ischemic oxidant stress, including antioxidants or scavengers of residual O(2) that attenuate/prevent ROS generation during ischemia, abrogated cell death during simulated reperfusion. These findings reveal that, in isolated cardiomyocytes, sublethal H(2)O(2) generation during simulated ischemia regulates cell death during simulated reperfusion, which is mediated by the reperfusion oxidant burst.

1021: Selective Nuclear Factor Kappa B(NFκB) Inhibitor, Pyrolidium Dithiocarbamate Prevents, Long-Term Histologic Damage in Ischemia-Reperfusion Injury after Delayed Testicular Torsion

You have accessJournal of UrologyModerated Poster, Tuesday, May 23, 2006, 8:00 - 10:00 am1 Apr 20061021: Selective Nuclear Factor Kappa B(NFκB) Inhibitor, Pyrolidium Dithiocarbamate Prevents, Long-Term Histologic Damage in Ischemia-Reperfusion Injury after Delayed Testicular Torsion Sinan L. Kirecci, Emin Ozbek, Alper Otunctemur, Levent Ozcan, Adnan Somay, Volkan Tugcu, and A. Ihsan Tasci Sinan L. KirecciSinan L. Kirecci More articles by this author , Emin OzbekEmin Ozbek More articles by this author , Alper OtunctemurAlper Otunctemur More articles by this author , Levent OzcanLevent Ozcan More articles by this author , Adnan SomayAdnan Somay More articles by this author , Volkan TugcuVolkan Tugcu More articles by this author , and A. Ihsan TasciA. Ihsan Tasci More articles by this author View All Author Informationhttps://doi.org/10.1016/S0022-5347(18)33246-4AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail "1021: Selective Nuclear Factor Kappa B(NFκB) Inhibitor, Pyrolidium Dithiocarbamate Prevents, Long-Term Histologic Damage in Ischemia-Reperfusion Injury after Delayed Testicular Torsion." The Journal of Urology, 175(4S), p. 329 © 2016 by American Urological AssociationFiguresReferencesRelatedDetails Volume 175Issue 4SApril 2006Page: 329 Advertisement Copyright & Permissions© 2016 by American Urological AssociationMetricsAuthor Information Sinan L. Kirecci More articles by this author Emin Ozbek More articles by this author Alper Otunctemur More articles by this author Levent Ozcan More articles by this author Adnan Somay More articles by this author Volkan Tugcu More articles by this author A. Ihsan Tasci More articles by this author Expand All Advertisement PDF DownloadLoading ...