Subsequent Oxidative Injury Research Articles

Chlorogenic acid induces endoplasmic reticulum stress in Botrytis cinerea and inhibits gray mold on strawberry

Chlorogenic acid (CGA) is a plant-derived compound with antifungal activity. However, the antifungal mechanism of CGA remains not fully revealed. The antifungal effect of CGA against Botrytis cinerea was assessed in the present study, and its mode of action was studied. Results demonstrated that CGA suppressed the growth of B. cinerea, as well as the development of gray mold (B. cinerea) on strawberry. Further analysis indicated that CGA induced endoplasmic reticulum (ER) stress in hyphae of B. cinerea resulting in an efflux of calcium (Ca2+) from the ER to the cytoplasm and then into mitochondria. The Ca2+ overload in mitochondria elicited the Ca2+-calmodulin-calcineurin cascade, resulting in a superoxide burst in the mitochondria. Finally, a decrease in ATP content and cell viability was observed in B. cinerea. This is the first report showing that the inhibitory effect of CGA towards B. cinerea involves an ER stress, followed by a Ca2+ release from the ER to the mitochondria, resulting in a superoxide burst and subsequent oxidative injury that reduces cell viability. Thus, CGA can be considered as an effectively substance to control gray mold on strawberry.

Choroid plexus imaging to track neuroinflammation - a translational model for mouse and human studies.

Choroid plexus imaging to track neuroinflammation - a translational model for mouse and human studies.

Pterostilbene Attenuates Cocultured BV-2 Microglial Inflammation-Mediated SH-SY5Y Neuronal Oxidative Injury via SIRT-1 Signalling

Microglial inflammation plays an important part in the progression of multiple neurological diseases, including neurodegenerative diseases, stroke, depression, and traumatic encephalopathy. Here, we aimed to explore the role of pterostilbene (PTE) in the microglial inflammatory response and subsequent damage of cocultured neural cells and partially explain the underlying mechanisms. In the coculture system of lipopolysaccharide-activated BV-2 microglia and SH-SY5Y neuroblastoma, PTE (only given to BV-2) exhibited protection on SH-SY5Y cells, evidenced by improved SH-SY5Y morphology and viability and LDH release. It also attenuated SH-SY5Y apoptosis and oxidative stress, evidenced by TUNEL and DCFH-DA staining, as well as MDA, SOD, and GSH levels. Moreover, PTE upregulated SIRT-1 expression and suppressed acetylation of NF-κB p65 subunit in BV-2 microglia, thus decreasing the inflammatory factors, including TNF-α and IL-6. Furthermore, the effects above were reversed by SIRT-1 inhibitor EX527. These results suggest that PTE reduces the microglia-mediated inflammatory response and alleviates subsequent neuronal apoptosis and oxidative injury via increasing SIRT-1 expression and inhibiting the NF-κB signalling pathway.

Carbon Monoxide Rescues the Developmental Lethality of Experimental Rat Models of Rhabdomyolysis-Induced Acute Kidney Injury.

Many victims, after being extricated from a collapsed building as the result of a disaster, suffer from disaster nephrology, a term that is referred to as the crush syndrome (CS). Recommended treatments, which include dialysis or the continuous administration of massive amounts of fluid are not usually easy in cases of such mass natural disasters. In the present study, we examined the therapeutic performance of a biomimetic carbon monoxide (CO) delivery system, CO-enriched red blood cells (CO-RBCs), on experimental animal models of an acute kidney injury (AKI) induced by traumatic and nontraumatic rhabdomyolysis, including CS and rhabdomyolysis with massive hemorrhage shock. A single CO-RBC treatment was found to effectively suppress the pathogenesis of AKI with the mortality in these model rats being improved. In addition, in further studies using glycerol-induced rhabdomyolysis model rats, the pathogenesis of which is similar to that for the CS, AKI and mortality were also reduced as the result of a CO-RBC treatment. Furthermore, CO-RBCs were found to have renoprotective effects via the suppression of subsequent heme protein-associated renal oxidative injury; the oxidation of myoglobin in the kidneys, the generation of reactive oxygen species by free heme produced from degraded-cytochrome P450 and hemoglobin-associated renal injury. Because CO-RBCs can be prepared and used at both hospitals and at a disaster site, these findings suggest that CO-RBCs have the potential for use as a novel cell therapy against both nontraumatic and traumatic rhabdomyolysis including CS-induced AKI. SIGNIFICANCE STATEMENT: After mass natural and man-made disasters, people who are trapped in collapsed buildings are in danger of acute kidney injury (AKI), including crush syndrome (CS)-related AKI. This paper reports that carbon monoxide-enriched red blood cells (CO-RBCs), which can be prepared at both hospitals and disaster sites, dramatically suppressed the pathogenesis of CS-related AKI, thus improving mortality via suppressing heme protein-associated renal injuries. CO-RBCs have the potential for serving as a practical therapeutic agent against disaster nephrology associated with the CS.

Scutellarin alleviates blood-retina-barrier oxidative stress injury initiated by activated microglia cells during the development of diabetic retinopathy

The breakdown of blood-retinal barrier (BRB) is an early and typical event during the development of diabetic retinopathy (DR). Scutellarin (SC) is a natural flavonoid. This study aims to investigate the protection of SC from BRB damage via focusing on inhibiting microglia-initiated inflammation and subsequent oxidative stress injury. SC attenuated BRB breakdown and the reduced expression of claudin-1 and claudin-19 in STZ-induced diabetic mice. SC reduced microglia cells activation both in vivo and in vitro. The results of transendothelial/transepithelial electrical resistance (TEER/TER) and fluorescein isothiocyanate (FITC)-conjugated dextran cell permeability assay showed that SC attenuated BRB damage induced by d-glucose (25 mM)-stimulated microglia BV2 cells. SC suppressed nuclear factor κB (NFκB) activation and tumor necrosis factor (TNF)-α expression induced by d-glucose (25 mM) in BV2 cells. SC decreased the phosphorylation of extracellular regulated protein kinase (ERK)1/2 both in vivo and in vitro. MEK1/2 inhibitor U0126 reduced the d-glucose-induced NFκB nuclear accumulation and TNFα expression in BV2 cells. Next, SC improved the decreased expression of claudin-1 and claudin-19, the increased BRB damage and cellular reactive oxygen species (ROS) formation, and enhanced nuclear accumulation of nuclear factor erythroid 2-related factor 2 (Nrf2) in TNFα-treated human retinal endothelial cells (HRECs) and APRE19 cells. Moreover, the SC-provided alleviation on BRB breakdown in STZ-induced diabetic mice was diminished in Nrf2 knock-out mice. In conclusion, SC alleviates BRB breakdown via abrogating retinal inflammatory responses and subsequent oxidative stress injury initiated by microglia cells that is activated by hyperglycemia during DR development.

Evaluation and physiological correlation of plasma proteomic fingerprints for deltamethrin-induced hepatotoxicity in Wistar rats

AimsUprising reports towards deltamethrin (DLM)-induced toxicity in non-target species including mammals have raised a worldwide concern. Moreover, in the absence of any identified marker, the prediction of DLM elicited early toxic manifestations in non-targets remains elusive. Main methodsComprehensive approach of proteome profiling along with conventional toxico-physiological correlation analysis was performed to classify novel protein based markers in the plasma of DLM exposed Wistar rats. Animals were exposed orally to DLM (low dose: 2.56mg/kg b.wt. and high dose: 5.12mg/kg b.wt.) up to seven consecutive days. Key findingsThe UPLC-MS/MS analysis revealed a dose-dependent dissemination of DLM and its primary metabolite (3-Phenoxy benzoic acid) in rat plasma. Through 2-DE-MS/MS plasma profiling and subsequent verification at the transcriptional level, we found that 6 liver emanated acute phase proteins (Apolipoprotein-AIV, Apolipoprotein E, Haptoglobin, Hemopexin, Vitamin D Binding protein, and Fibrinogen gamma chain) were significantly (p<0.05) modulated in DLM treated groups in a dose-dependent manner. Accordingly, DLM exposure resulted in adverse effects on body growth (body weight & relative organ weight), serum profile, liver function and histology, inflammatory changes (enhanced TNF-ɑ, TGF-β and IL6 level), and oxidative stress. Moreover, these toxic manifestations were suppressed upon N-acetyl cysteine (NAC) supplementation in DLM treated animals. Thus, DLM-induced inflammatory response and subsequent oxidative injury to liver grounds the altered expression of identified acute phase proteins. SignificanceIn conclusion, we proposed these six liver emanated plasma proteins as novel candidate markers to assess the early DLM-induced hepatotoxicity in non-target species with a minimal invasive mean.

Current Antioxidant Treatments in Organ Transplantation.

Oxidative stress is one of the key mechanisms affecting the outcome throughout the course of organ transplantation. It is widely believed that the redox balance is dysregulated during ischemia and reperfusion (I/R) and causes subsequent oxidative injury, resulting from the formation of reactive oxygen species (ROS). Moreover, in order to alleviate organ shortage, increasing number of grafts is retrieved from fatty, older, and even non-heart-beating donors that are particularly vulnerable to the accumulation of ROS. To improve the viability of grafts and reduce the risk of posttransplant dysfunction, a large number of studies have been done focusing on the antioxidant treatments for the purpose of maintaining the redox balance and thereby protecting the grafts. This review provides an overview of these emerging antioxidant treatments, targeting donor, graft preservation, and recipient as well.

S3-4 - NASH (Nonalcoholic steatohepatitis): A case of multiorganelle failure

The clinical term 'multiorgan failure' lends itself, modified to 'multiorganelle failure', to the cascading events in cellular systems leading to hepatocyte injury, cell death, inflammation and fibrosis and ultimately to cirrhosis in NASH (non-alcoholic steatohepatitis). NASH is one of the most common forms of liver disease and constitutes the severe form of NAFLD (non-alcoholic fatty liver disease). The key features that distinguish potentially progressive NASH from relatively stable non-NASH fatty liver (NNFL, often referred to as simple steatosis) are cellular ballooning, inflammation and fibrosis. These findings, together with steatosis or accumulation of greater than normal hepatic lipid, usually constitute histological NASH seen on liver biopsy or in laboratory samples. Cellular ballooning is not specific to NASH but it is perhaps the most emblematic finding on histological samples. The ballooned hepatocyte has evidence of cytoskeletal injury (depletion and condensation as Mallory-Denk bodies), accumulation of partially oxidized small fat droplets, mitochondrial morphological changes presumably related to organelle dysfunction, dilated endoplasmic reticulum and autophagosomes - an attempt at cellular repair. Ballooning itself likely results from a combination of cytoskeletal injury resulting in loss of normal cell shape and from accumulation of injured and somewhat derelict small fat droplets and dilated endoplasmic reticulum. Cellular injury in NASH and especially cellular ballooning can be viewed as a process of 'multi-organelle failure' beginning with generation of super oxide and failure to contain the subsequent oxidative injury and by-products in an environment rich in lipid fuel. These events lead to activation of imunologic pathways. Dysfunction of the small fat droplet appears to be a central mechanism and the oxidative injury can be viewed as the process of rancidification - the chemical decomposition of oils, lipids and fats.

Oleic acid promotes adaptability against oxidative stress in 3T3-L1 cells through lipohormesis

Although fatty acids are important components of biological membranes, energy sources, and signal transducers or precursors of lipid mediators, excess intake of fatty acids and their accumulation cause obesity and metabolic syndrome. Thus, fatty acid quantity is known to be an important factor for obesity-related diseases, but the effects of different types of fatty acids (i.e., fatty acid quality) on human health are not completely understood. We here focused on the relationship between fatty acid quality and oxidative stress by investigating whether resistibility to tert-butyl hydrperoxide (t-BuOOH)-induced oxidative stress in 3T3-L1 cells varied according to the fatty acid type. Among eight fatty acids (both saturated and unsaturated) tested, oleic acid (OA) exerted the most pronounced cytoprotective effects, with efficacy over a wide range of concentrations. OA treatment markedly enhanced the intracellular levels of lipid peroxidation markers, including N(ε)-(hexanoyl)lysine, 4-hydroxy-2-nonenal, and acrolein. The levels of these markers in OA-treated cells were decreased after t-BuOOH exposure, whereas the levels in untreated control cells were notably increased after t-BuOOH exposure. Our results suggested that unsaturated fatty acids, particularly OA, could promote an adaptive response and enhance cell tolerance through increased cellular antioxidative capacity via OA-induced mild lipid peroxidation (lipohormesis), and thus protect cells against subsequent oxidative stress-related injury.

PTU-107 Nafld in Patients with Severe Asthma

IntroductionNAFLD is a spectrum of liver disease that encompasses Nonalcoholic fatty liver (NAFL) and nonalcoholic steatohepatitis (NASH). The pathophysiology is not fully understood, but is believed to be a combination...

Pravastatin prevents miscarriages in antiphospholipid antibody-treated mice

Miscarriages in patients with antiphospholipid (aPL) antibodies have been attributed to thrombosis of placental vessels. However, we have shown that inflammation plays a crucial role in fetal injury. We identified tissue factor (TF), the major cellular activator of the coagulation cascade, as a key mediator in inflammation and fetal injury in aPL antibody-treated mice. We found that TF in maternal neutrophils was associated with fetal injury. TF expression in neutrophils contributes to the respiratory burst and subsequent trophoblast oxidative injury and pregnancy loss induced by aPL antibodies. We also analysed how TF contributes to neutrophil activation and trophoblast injury in this model. We showed that neutrophils from aPL antibody-treated mice express protease activated receptor 2 (PAR-2) and that stimulation of this receptor leads to neutrophil activation, trophoblast injury and fetal death. Mice deficient in PAR-2 and treated with aPL antibodies exhibited reduced neutrophil activation and normal pregnancies, indicating that PAR-2 plays an important role in the pathogenesis of aPL antibody-induced fetal injury. In addition, we demonstrated that the statins simvastatin and pravastatin downregulate TF and PAR-2 expression in neutrophils and thus prevent pregnancy loss. In summary, this study shows that TF signaling through PAR-2 mediates neutrophil activation and fetal death in antiphospholipid syndrome, and that statins may be an appropriate treatment for women with aPL antibody-induced pregnancy complications.

Enhancement of PPAR-β activity by repetitive low-grade H2O2 stress protects human umbilical vein endothelial cells from subsequent oxidative stress-induced apoptosis

Repetitive stress has been shown to up-regulate antioxidant defense and increase survival after subsequent oxidative injury. The up-regulation of antioxidant defense has been identified as an underlying cause of the apoptosis-inhibitory effects exerted by repetitive stress. However, it remains unclear what the important signaling mechanisms are by which cells preexposed to low-grade stress deal with apoptosis-inducing stress. In this study, we repetitively stressed human umbilical vein endothelial cells (HUVECs) through multiple exposures to a low dose (30 μM) of H2O2 in culture for 4 weeks. We then examined the effects of repetitive stress on PPAR-β expression and activity as well as the role of PPAR-β in the protective potency of repetitive stress. Our results show that repetitive stress enhances PPAR-β expression and activity, thereby inhibiting oxidative stress-induced apoptosis. Further, PPAR-β-directed antisense oligonucleotides reduced the PPAR-β protein content, enhanced the H2O2-mediated apoptosis, and ablated the protective effect of repetitive low-grade H2O2 stress. The specific PPAR-β agonist L-165041 significantly potentiated the apoptosis induced by H2O2 (p<0.05) and increased the protective effect of repetitive stress. These findings indicate that repetitive low-grade H2O2 stress protects HUVECs from subsequent oxidative stress-induced apoptosis by enhancing PPAR-β expression and activity.

Dopamine as a Potent Inducer of Cellular Glutathione and NAD(P)H:Quinone Oxidoreductase 1 in PC12 Neuronal Cells: A Potential Adaptive Mechanism for Dopaminergic Neuroprotection

Dopamine auto-oxidation and the consequent formation of reactive oxygen species and electrophilic quinone molecules have been implicated in dopaminergic neuronal cell death in Parkinson's disease. We reported here that in PC12 dopaminergic neuronal cells dopamine at noncytotoxic concentrations (50-150 muM) potently induced cellular glutathione (GSH) and the phase 2 enzyme NAD(P)H:quinone oxidoreductase 1 (NQO1), two critical cellular defenses in detoxification of ROS and electrophilic quinone molecules. Incubation of PC12 cells with dopamine also led to a marked increase in the mRNA levels for gamma-glutamylcysteine ligase catalytic subunit (GCLC) and NQO1. In addition, treatment of PC12 cells with dopamine resulted in a significant elevation of GSH content in the mitochondrial compartment. To determine whether treatment with dopamine at noncytotoxic concentrations, which upregulated the cellular defenses could protect the neuronal cells against subsequent lethal oxidative and electrophilic injury, PC12 cells were pretreated with dopamine (150 muM) for 24 h and then exposed to various cytotoxic concentrations of dopamine or 6-hydroxydopamine (6-OHDA). We found that pretreatment of PC12 cells with dopamine at a noncytotoxic concentration led to a remarkable protection against cytotoxicity caused by dopamine or 6-OHDA at lethal concentrations, as detected by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium reduction assay. In view of the critical roles of GSH and NQO1 in protecting against dopaminergic neuron degeneration, the above findings implicate that upregulation of both GSH and NQO1 by dopamine at noncytotoxic concentrations may serve as an important adaptive mechanism for dopaminergic neuroprotection.

Hypoxic preconditioning attenuates lipopolysaccharide-induced oxidative stress in rat kidneys.

Chronic hypoxic (CH) preconditioning reduces superoxide-induced renal dysfunction via the upregulation of superoxide dismutase (SOD) activity and contents. Endotoxaemia reduces renal antioxidant status. We hypothesize that CH preconditioning might protect the kidney from subsequent endotoxaemia-induced oxidative injury. Endotoxaemia was induced by intraperitoneal injection of lipopolysaccharide (LPS; 4 mg kg(-1)) in rats kept at sea level (SL) and rats with CH in an altitude chamber (5500 m for 15 h day(-1)) for 4 weeks. LPS enhanced xanthine oxidase (XO) and gp91phox (catalytic subunit of NADPH oxidase) expression associated with burst amount of superoxide production from the SL kidney surface and renal venous blood detected by lucigenin-enhanced chemiluminescence. LPS induced a morphologic-independent renal dysfunction in baseline and acute saline loading stages and increased renal IL-1beta protein and urinary protein concentration in the SL rats. After 4 weeks of induction, CH significantly increased Cu/ZnSOD, MnSOD and catalase expression (16 +/- 17, 128 +/- 35 and 48 +/- 21, respectively) in renal cortex, and depressed renal cortex XO (44 +/- 16%) and renal cortex (20 +/- 9%) and medulla (28 +/- 11%) gp91phox when compared with SL rats. The combined effect of enhanced antioxidant proteins and depressed oxidative proteins significantly reduced LPS-enhanced superoxide production, renal XO and gp91phox expression, renal IL-1beta production, and urinary protein level. CH also ameliorated LPS-induced renal dysfunction in the baseline and acute saline loading periods. We conclude that CH treatment enhances the intrarenal antioxidant/oxidative protein ratio to overcome endotoxaemia-induced reactive oxygen species formation and inflammatory cytokine release.

Sex and genetic associations with cerebrospinal fluid dopamine and metabolite production after severe traumatic brain injury

Dopamine (DA) pathways have been implicated in cognitive deficits after traumatic brain injury (TBI). Both sex and the dopamine transporter (DAT) 3' variable number of tandem repeat polymorphism have been associated with differences in DAT protein density, and DAT protein affects both presynaptic DA release, through reverse transport, and DA reuptake. Catecholamines and associated metabolites are subject to autooxidation, resulting in the formation of reactive oxygen species that may contribute to subsequent oxidative injury. The purpose of this study was to determine associations between factors that affect DAT expression and cerebrospinal fluid (CSF) DA and metabolite levels after severe TBI. Sixty-three patients with severe TBI (Glasgow Coma Scale score < or = 8) were evaluated. The patients' genotypes were obtained using previously banked samples of CSF, and serial CSF samples (416 samples) were used to evaluate DA and metabolite levels. High-performance liquid chromatography was used to determine CSF levels of DA, 3,4-dihydroxyphenylacetic acid (DOPAC), and homovanillic acid (HVA) during the first 5 days after injury. Mixed-effects multivariate regression modeling revealed that patients with the DAT 10/10 genotype had higher CSF DA levels than patients with either the DAT 9/9 or DAT 9/10 genotypes (p = 0.009). Females with the DAT 10/10 genotype had higher CSF DA levels than females with the DAT 9/9 or DAT 9/10 genotypes, and sex was associated with higher DOPAC levels (p = 0.004). Inotrope administration also contributed to higher DA levels (p = 0.002). In addition to systemic administration of DA, inherent factors such as sex and DAT genotype affect post-TBI CSF DA and DA metabolite levels, a phenomenon that may modulate susceptibility to DA-mediated oxidative injury.

Fatty acid-mediated intracellular iron translocation: A synergistic mechanism of oxidative injury

Fatty acid has been reported to be associated with cardiovascular diseases and cancer, but the possible mechanism remains unclear. Here, we reported a novel mechanism for the permissive role of fatty acid on iron intracellular translocation and subsequent oxidative injury. In vitro study from endothelial cells showed that iron alone had little effect, whereas in combination with PA (palmitic acid), iron-mediated toxicity was markedly potentiated, as reflected in mitochondrial dysfunction, cell death, apoptosis, and DNA mutation. We also showed that PA not only facilitated iron translocation into cells through a transferrin-receptor (TfR)-independent mechanism, but also translocated iron into mitochondria; the subsequent intracellular iron overload resulted in reactive oxygen species (ROS) overgeneration and lipid oxidation. Further investigation revealed that PA-facilitated iron translocation is due to Fe/PA-mediated extracellular oxidative stress and the subsequent membrane damage with increased membrane permeability. Fe/PA-mediated toxic effects were reduced in ρ0 cells lacking mitochondrial DNA or by antioxidant enzyme SOD, especially mitochondrially localized MnSOD, suggesting a permissive role of PA for iron deposition on the vascular wall and its subsequent toxicity via mitochondrial oxidative stress. This observation was confirmed in vivo in mice, wherein higher vascular iron deposition and accompanying superoxide release were observed in the presence of a high-fat diet with iron administration.

Research and Development of the Free Radical Scavenger Edaravone as a Neuroprotectant

AbstractFor Abstract see ChemInform Abstract in Full Text.

Research and development of the free radical scavenger edaravone as a neuroprotectant

Increasing data suggest that oxygen free radical species play detrimental roles in ischemic diseases. A free radical scavenger capable of inhibiting oxidative injury is expected to become a new drug for the treatment of ischemic diseases such as cerebral ischemia. Edaravon (3-methyl-1-phenyl-2-pyrazolin-5-one), which has been developed as an neuroprotective agent for more than 15 years since its discovery, is approved for the treatment of acute cerebral infarction. In this paper, the pharmacologic characteristics and clinical effects of edaravone are reviewed. In early stage of investigation, edaravone was found to have promising activities as an antioxidative radical scavenger, quenching hydroxyl radical (.OH) and inhibiting both .OH-dependent and .OH-independent lipid peroxidation. Edaravone showed inhibitory effects on both water-soluble and lipid-soluble peroxyl radical-induced peroxidation systems, which are different from the inhibitory effects of vitamins C and E in each system, respectively. Oxidative injury to cultured endothelial cells caused by arachidonate (AA) peroxides is prevented in the existence of edaravone. To clarify the characteristics of this free radical scavenger, further investigation was carried out. Edaravone ameliorated exacerbation of cortical edema induced by a focal ischemia-reperfusion model in rats, suggesting inhibitory effects on oxidative injury to the blood-brain barrier (BBB). Additionally, edaravone also prevented rat cortical edema caused by intracortical AA infusion in which free radical production and subsequent oxidative injury to the BBB are involved. With advances in in vivo measurement technology of oxygen radicals, edaravone was shown to inhibit postischemic increases in .OH production and tissue injury in the penumbral or recirculated area in rat cerebral ischemia models. In clinical studies, edaravone improved the core neurologic deficits, activities of daily living, and functional outcome of stroke patients. Furthermore, a study using proton magnetic resonance spectroscopic techniques showed that edaravone preserved N-acetyl-aspartate in stroke patients, a promising neuronal marker in the brain. Further investigation is essential for a better understanding of free radical-mediated cerebral injury during ischemia followed by recirculation. We hope that edaravone represents a promising neuroprotectant for drug therapy in acute cerebral ischemia.

Mitochondrial antioxidant function is a potential mechanism for organ differences in interleukin-1-mediated tolerance to oxidative injury.

Pretreatment with interleukin-1 (IL-1) induces resistance to lung injury from hyperoxia exposure and to cardiac dysfunction after ischemia-reperfusion in animal models. In contrast, IL-1 pretreatment did not produce tolerance to ischemia-reperfusion injury and did not seem to alter antioxidant enzyme activities in the kidney. Recently, we determined that mitochondria scavenge superoxide anion via a nonenzymatic mechanism and that this newly identified intracellular antioxidant function was inducible in the lung. Based on these observations, we hypothesized that organ differences after IL-1 pretreatment between the lung and the heart, which become tolerant, and the kidney, which does not become tolerant, were a consequence of differential responses in mitochondrial superoxide scavenging. Rats were given IL-1alpha (50 ng intratracheally, 36 hrs before assay) and lung and kidney mitochondria were isolated. Mitochondrial scavenging of superoxide anion was then determined by using an assay that we developed and published previously. We then tested the effects of IL-1 pretreatment on lung mitochondrial scavenging of superoxide after hyperoxia exposure. We found that intratracheal administration of IL-1 did not affect lung mitochondrial superoxide scavenging but decreased kidney mitochondrial superoxide scavenging by 75%. In addition, IL-1 pretreatment preserved lung mitochondrial superoxide scavenging in rats exposed to hyperoxia (95% O2 for 24 hours) compared with untreated rats exposed to hyperoxia in which lung mitochondrial superoxide scavenging was decreased by more than 50%. We conclude that IL-1 pretreatment has divergent effects on mitochondrial antioxidant function in the lung and the kidney and speculate that this may reflect previously unidentified tissue-specific differences in mitochondrial function during systemic inflammation. This study offers new insights into why the lung, but not the kidney, acquires tolerance to subsequent oxidative injury after IL-1 pretreatment.

Induction of heat shock protein 70 protects mesangial cells against oxidative injury

The heat shock response is an immediate cellular response to elevated temperatures and other types of injury that consists of the synthesis of so-called heat shock protein (hsp). This study was designed to investigate the production and the protective role of the 70 kDa hsp (hsp70) in cultured rat mesangial cells. When mesangial cells undergo thermal (45 degrees C, 15 min) stimulation, they express hsp70 mRNA expression and increased hsp70 protein production. Following this, Northern blots show an enhanced gene expression of hsp70 at one hour that reached a maximum by 12 hours after heat shock. The hsp70 protein production, estimated by Western blots, was detectable 12 hours after heat shock and reached a maximum by 36 hours. Oxidative injury generated by xanthine and xanthine oxidase inhibited cell survival and cellular proliferation, as measured by trypan blue exclusion and [3H]-labeled thymidine uptake. It did not affect hsp70 mRNA expression. Furthermore, when mesangial cells were preconditioned by heat shock, subsequent oxidative injury caused less inhibition of cell survival and cellular proliferation. Pretreatment of cells with quercetin, a transcription inhibitor, abolished the protective effect of heat shock on subsequent oxidative injury. We conclude that heat shock, not oxidative injury, induces hsp70 in mesangial cells, and this induction of hsp70 protects mesangial cells against subsequent oxidative injury.