Cyclosporine A-induced apoptosis in renal tubular cells is related to oxidative damage and mitochondrial fission

Cyclosporine A (CsA) nephrotoxicity has been linked to reactive oxygen species (ROS) production in renal cells. We have demonstrated that the antioxidant Vitamin E (Vit E) abolished renal toxicity in vivo and in vitro models. As one of the main sources of intracellular ROS are mitochondria, we studied the effects of CsA on several mitochondrial functions in LLC-PK1 cells.     

Pyruvate kinase is protected by glutathione-dependent redox balance in human red blood cells exposed to reactive oxygen species

To determine the antioxidant role of glutathione (GSH) in human red blood cells (RBCs), we investigated the effect of disrupting GSH homeostasis on the oxidative modification of thiol-dependent enzymes by exposure to tert-butyl hydroperoxide (BHP). When hemolysate was incubated with BHP, significant decreases in enzyme activity were observed. However, the inactivation did not occur in intact RBC suspensions that were exposed to BHP. In this study, we used two independent treatments aimed at decreasing the level of reduced form of GSH, pre-incubation with a glutathione reductase inhibitor or glucose-free medium to examine the influences of preventing GSH-dependent antioxidant and reactivation activity on thiol-dependent enzyme. Pyruvate kinase (PK) activity clearly decreased along with depletion of GSH compared to other glycolytic enzyme activities by BHP exposure in RBCs. The addition of GSH, but not glucose, before BHP exposure completely prevented the inactivation of PK in hemolysate; however, partial reactivation of inactivated PK was observed by post-addition of both GSH and glutaredoxin at an early stage during BHP exposure. Moreover, hydroxyl radicals but not hydrogen peroxide inactivated PK. These results suggest that PK is highly susceptible to radicals and that GSH is essential to protect PK activity by not only directly scavenging radicals but also by systematically reactivating oxidized enzyme in human RBCs.     

Cyclosporine and lactation: when the mother is willing to breastfeed

We describe a woman treated with cyclosporine after renal transplantation who commenced breastfeeding of her newborn infant. The child had no apparent clinical adverse effects to cyclosporine. To confirm the safety of breastfeeding and guide the patient and her clinician, cyclosporine concentrations in maternal blood, breast milk, and infant blood were measured. Maternal cyclosporine concentration (1-hour postdose) was 49 μg/L, and the breast milk cyclosporine concentration (2-hour postdose) was 46 μg/L. Infant cyclosporine blood concentration shortly after breastfeeding was undetectable (<10 μg/L). Analysis revealed that the estimated infant exposure to cyclosporine via breast milk was minimal and provided reassurance to continue breastfeeding in this case.     

Cyclosporine A treated in vitro models induce cholestasis response through comparison of phenotype-directed gene expression analysis of in vivo Cyclosporine A-induced cholestasis

In vitro models for hepatotoxicity testing are a necessity for advancement of toxicological research. Assessing the in vitro response requires in vivo validated gene sets reflective of the hepatotoxic phenotype. Cholestasis, the impairment of bile flow, is induced in C57BL/6J mice treated with cyclosporine A (CsA) to identify phenotype reflective gene sets. CsA treatment through oral gavage for 25 days induced cholestasis, as confirmed by histopathology and serum chemistry. Over 1, 4, and 11 days of CsA exposure gradual increases in serum markers were correlated to gene expression. This phenotype-directed analysis identified gene sets specific to the onset and progression of cholestasis, such as PPAR related processes and drug metabolism, by circumventing other effects of CsA, such as immunosuppression, found in dose*time group analysis. In vivo gene sets are enriched in publicly available data sets of CsA-treated HepaRG and primary mouse hepatocytes. However, genes identified within these gene sets did not overlap between in vivo and in vitro. In vitro regulated genes represent the initial response to cholestasis, whereas in vivo genes represent the later adaptive response. We conclude that the applicability of in vitro models for hepatotoxicity testing fully depends on a solid in vivo phenotype anchored analysis.     

Phenanthrene decreases neutrophil function by disrupting intracellular redox balance

The aim of the present work was to evaluate whether the treatment of human neutrophils with phenanthrene (PHN) can alter the phagocytic and microbicidal capacity of these cells by causing a disruption in redox balance. Peripheral neutrophils from healthy subjects were treated for up to 24 h with increasing concentrations of phenanthrene. Phagocytic/microbicidal activities, antioxidant enzymes, oxidative lesions (thiobarbituric acid‐reactive substances and protein thiol and carbonyl groups) and redox signaling compounds (intracellular Ca²⁺, superoxide, hydrogen peroxide and nitric oxide) were monitored on neutrophils exposed to 10 µg PHN ml^?1. Cell viability decreased abruptly at PHN concentrations above 10 µg ml^?1 (LC50 = 20.86 ± 0.51 µg ml^?1 and p‐sigmoidal slope = 19.88 ± 10.11). Phagocytic and microbicidal capacities were decreased by 60 and 82%, respectively. Substantial increases in total‐/Mn‐SOD, catalase, glutathione peroxidase and glutathione reductase activities (by 61, 15, 87, 245 and 70%, respectively) matched the oxidative injury obtained in TBARS (2.5‐fold higher) and protein thiol (54% lower). Diminished productions of superoxide by 18% and hydrogen peroxide by 29% were observed in association to exacerbated calcium (27%) and nitric oxide (63%) levels. The data indicate that phenanthrene might be associated with substantial reduction in human neutrophil functions due to severe intracellular redox imbalances. Copyright © 2010 John Wiley & Sons, Ltd.     

Effect of Propofol, Sevoflurane and Desflurane on systemic redox balance

We studied the effects of Propofol, Desflurane, and Sevoflurane on the systemic redox balance in patients undergoing laparohysterectomy. We measured blood concentration of glutathione (GSH), plasma antioxidant capacity (Trolox Equivalent Antioxidant Capacity-TEAC), and lipid peroxidation products (malondialdehyde (aMDA) and 4-hydroxynonenal (aHNE) protein adducts). Sixty patients were randomly placed into three groups of twenty people each. In Group P anesthesia was induced with Propofol 2 mg/kg and maintained with 12-10-8 mg/kg/min; in Groups S and D anesthesia was induced with 3 mg/kg Sodium Thiopental and maintained with 2 percent Sevoflurane and 6 percent Desflurane, respectively. Blood samples were collected prior to induction (T0 bas), 60min and 24h postoperatively (T1 60 and T2 24 h). In Group P, GSH increased on T1 60 and returned to baseline on T24h, while TEAC remained unmodified; in Groups S, GSH and TEAC decreased on T1 60 in Group D, on T1 60 there was a slight decrease of GSH and TEAC. The levels of aMDA slightly decreased throughout the study periods in Group P, increased in Group D, and remained stable in Group S. Propofol showed antioxidant properties, while Sevoflurane and Desflurane seemed to shift the redox balance towards oxidation, yet without inducing overt oxidative damage.     

Ochratoxin A-induced porcine nephropathy: enzyme and ultrastructure changes after short-term exposure

Four pigs were treated with ochratoxin A (800 micrograms/kg) for five consecutive days. Subsequently, urine and bile were collected and kidneys were perfusion fixed unilaterally. Liver and kidney samples were examined for the distribution of ochratoxin A and metabolites in subcellular fractions and the effects of the toxin on protein synthesis and enzyme activities. Ochratoxin A and the hydrolytic product, ochratoxin alpha, were found in urine. Elevated levels of toxin accumulation in kidney (283 ng/g) compared with liver (189 ng/g) and toxin-mediated reductions in protein synthesis and enzyme activities in kidney identified it as a target organ of ochratoxin toxicity. Ultrastructural investigations of kidney in toxin-exposed animals identified a process of condensation of cellular material with disappearance of membranes and continuous desquamation in the lower part of the proximal convoluted tubules. In target cells peroxisomes appeared to have lost membrane integrity and the organelles were leaking materials into the cytosol. Reduction of structural integrity was associated with an increase in the presence of catalase and cyanide insensitive fatty acid oxidase activity in the soluble kidney fractions.     

Monophosphoryl lipid A-induced delayed preconditioning is mediated by calcitonin gene-related peptide

The delayed preconditioning of the heart by monophosphoryl lipid A is mediated by endogenous nitric oxide (NO), and the cardioprotection afforded by nitroglycerin is related to stimulation of calcitonin gene-related peptide (CGRP) release. The objective of this study was to explore whether improvement of preservation with cardioplegia by monophosphoryl lipid A is mediated by CGRP. In addition, we examined the effect of monophosphoryl lipid A on the tumor necrosis factor-alpha (TNF-alpha) content of myocardial tissues. The isolated rat heart was perfused in the Langendorff mode. Heart rate, coronary flow, left-ventricular pressure, and its first derivatives (+/-dp/dt(max)) were recorded, and plasma levels of NO and CGRP, the release of creatine kinase in coronary effluent and the content of TNF-alpha in myocardial tissues were measured. Hypothermic ischemia for 4 h caused a decline in cardiac function, and an increase in the release of creatine kinase and in the content of TNF-alpha. Pretreatment with monophosphoryl lipid A (500 microg/kg, i.p.) for 24 h improved the recovery of cardiac function and reduced the release of creatine kinase concomitantly with a decrease in the content of cardiac TNF-alpha. Monophosphoryl lipid A markedly increased plasma concentrations of CGRP and NO. After pretreatment with L-nitroarginine methyl ester (L-NAME), the cardioprotection and the increased release of NO and CGRP induced by monophosphoryl lipid A were abolished. Capsaicin also abolished the cardioprotection and the increased release of CGRP induced by monophosphoryl lipid A, but did not affect the content of NO. The results suggest that monophosphoryl lipid A-induced preconditioning enhances preservation with cardioplegia and that the protective effects of monophosphoryl lipid A are related to stimulation of CGRP release.     

由微生态平衡的变化引起的有机体的熵变

本文从熵的角度说明生命过程进而解释有机体的状态变化的物理本质。生命体的各个系统在正常状态和疾病状态时,都对应着一定的熵值。当有机体内微生态平衡发生变化时,机体将产生相应的反应,出现某些疾病现象,这时相应的熵值也就发生改变。而物与细菌或病毒作用时,熵又可反映出其敏感性程度。     

Quercetin alleviates bisphenol A-induced changes in nucleic acid and protein contents in mice

The present study was an attempt to examine toxic effects of bisphenol A in liver and kidney of mice and its alleviation by quercetin. Oral administration of bisphenol A (60 and 120 mg/kg b. w./day) for 30 days caused, as compared to vehicle control significant, dose-dependent decrease in DNA, RNA and protein contents in liver and kidney of mice. Supplementation of quercetin (60 mg/kg b. w./day) along with bisphenol A for 30 days caused, as compared to bisphenol A alone treated groups, significant alleviation in DNA, RNA and protein contents. The amelioration was comparatively higher for high dose bisphenol A plus quercetin treated group than that of low dose plus quercetin treated group.     

Bisphenol A-induced epithelial to mesenchymal transition is mediated by cyclooxygenase-2 up-regulation in human endometrial carcinoma cells

Many studies have highlighted the correlation between the increase of bisphenol A (BPA) level in the environment and the incidence of tumor in humans. In human carcinogenesis, the overexpression of cyclooxygenase-2 (COX-2) and epithelial-mesenchymal transition (EMT) are closely related with tumor development. In this study, human endometrial carcinoma cells line (RL95-2) was used to investigate whether BPA can induce EMT and COX-2 expression. The results show that BPA increased growth rate and colony-forming efficiency in a dose-dependent manner, induced EMT and COX-2 gene expression and promoted the migration and invasion ability of RL95-2 cells. Furthermore, our study showed that the expression of COX-2 was essential for BPA-induced cell migration and invasion. The results of this study provide new insights into the mechanism of endometrial cancer cell growth and invasion and potential therapeutic strategy.     

Cyclosporine monitoring in renal transplantation: area under the curve monitoring is superior to trough-level monitoring

Trough levels (TL) of cyclosporine (CS) measured in serum by the polyclonal radioimmunoassay (SR) are useful for dissecting the etiology of clinical events, but they are a poor guide to dosage adjustments. In renal transplant patients immunosuppressed by low doses of prednisone and CS given orally, once-a-day TL (24-h) monitoring was replaced by area under the curve (AUC) monitoring, i.e., measuring the area under the concentration (SR)-time curve from seven blood samples (0, 2, 4, 6, 10, 14, and 24 h) at clinical steady state, which was reached on the 3rd day after a change in the oral dose rate. The therapeutic target was an average concentration at steady state (Css av) of 200 ng/ml during the first 6 months after transplantation and 150 ng/ml thereafter. The Css av was calculated by dividing the AUC by the dosing interval (24 h). Two findings demonstrated the superiority of AUC monitoring over TL monitoring. First, in 71 paired observations AUC but not TL was significantly correlated with the dose expressed as total mg (r = 0.381, p = 0.001) or mg/kg body weight (r = 0.538, p = 0.0001). Second, after adjusting (n = 26) the oral dose rate (to achieve the therapeutic target) the absolute error (i.e., deviation from the target) in the AUC observation (15%) was significantly (p = 0.0005) smaller than in the TL observation (36%). Monitoring AUC at clinical steady state reduced the number of dosage adjustments by a factor of 3.     

Cyclosporin A-induced free radical generation is not mediated by cytochrome P-450

1. Reactive oxygen species (ROS) have been proposed to play a role in the side effects of the immunosuppressive drug cyclosporin A (CsA). 2. The aim of this study was to investigate whether cytochrome P-450 (CYP) dependent metabolism of CsA could be responsible for ROS generation since it has been suggested that CsA may influence the CYP system to produce ROS. 3. We show that CsA (1 -- 10 microM) generated antioxidant-inhibitable ROS in rat aortic smooth muscle cells (RASMC) using the fluorescent probe 2,7-dichlorofluorescin diacetate. 4. Using cytochrome c as substrate, we show that CsA (10 microM) did not inhibit NADPH cytochrome P-450 reductase in microsomes prepared from rat liver, kidney or RASMC. 5. CsA (10 microM) did not uncouple the electron flow from NADPH via NADPH cytochrome P-450 reductase to the CYP enzymes because CsA did not inhibit the metabolism of substrates selective for several CYP enzymes that do not metabolize CsA in rat liver microsomes. 6. CsA (10 microM) did not generate more radicals in CYP 3A4 expressing immortalized human liver epithelial cells (T5-3A4 cells) than in control cells that do not express CYP 3A4. 7. Neither diphenylene iodonium nor the CYP 3A inhibitor ketoconazole were able to block ROS formation in rat aortic smooth muscle or T5-3A4 cells. 8. These results demonstrate that CYP enzymes do not contribute to CsA-induced ROS formation and that CsA neither inhibits NADPH cytochrome P-450 reductase nor the electron transfer to the CYP enzymes.     

Reduced cellular redox status induces 4-hydroxynonenal-mediated caspase 3 activation leading to erythrocyte death during chronic arsenic exposure in rats

Chronic exposure to arsenic in rats led to gradual accumulation of the toxicant in erythrocytes causing oxidative stress in these cells. 4-Hydroxynonenal (4-HNE), a major aldehyde product of lipid peroxidation, contributed significantly to the cytopathological events observed during oxidative stress in the erythrocytes of exposed rats. 4-HNE triggered death signal cascade that was initiated with the formation of HNE-protein adducts in cytosol. HNE-protein adduct formation resulted in depletion of cytosolic antioxidants followed by increased generation of ROS. Results showed accumulation of hydrogen peroxide (H₂O₂) from the early stages of arsenic exposure, while superoxide (O₂^•−) and hydroxyl radical (^•OH) also contributed to the oxidative stress during longer period of exposure. Suppression of antioxidant system coupled with increased generation of ROS eventually led to activation of caspase 3 during arsenic exposure. Attenuation of HNE-mediated activation of caspase 3 in presence of N-acetylcysteine (NAC) indicated the involvement of GSH in the process. Prevention of HNE-mediated degradation of membrane proteins in presence of Z-DEVD-FMK identified caspase 3 as the principal mediator of HNE-induced cellular damage during arsenic exposure. Degradation of band 3 followed by its aggregation on the red cell surface promoted immunologic recognition of redistributed band 3 by autologous IgG with subsequent attachment of C3b. Finally, the formation of C3b-IgG-band 3 immune complex accelerated the elimination of affected cells from circulation and led to the decline of erythrocyte life span during chronic arsenic toxicity.     

Mitochondrial state 3 to 4 respiration transition during Fas-mediated apoptosis controls cellular redox balance and rate of cell death

The role of reactive oxygen species (ROS) production in death receptor-mediated apoptosis is ill defined. We show that ROS levels play a novel role in moderating the rate of cell death in Fas-dependent apoptosis. Treatment of Jurkat T cells with oligomycin (ATP-synthase inhibitor) or FCCP (mitochondrial uncoupler) and Fas activating antibody (CH11), facilitated rapid cell death. ATP levels, DEVDase activity and cytochrome c release were not account for the synergistic killing effect. However, a decrease in cellular ROS production was associated with CH11 treatment and combinations of CH11 with oligomycin or FCCP further inhibited cellular ROS levels. Thus, decreased ROS production is correlated with accelerated cell death. A transition from state 3 to state 4 mitochondrial respiration following apoptotic stimuli accounted for an attenuated membrane potential and as a results mitochondria-derived ROS production capacity diminished. Similar observations were demonstrated in isolated rat liver mitochondria. Transfection with mitochondrial targeted catalase inhibited mitochondrial ROS production and potentiated cell death. These data show that ROS production is important in receptor-mediated apoptosis and may play a pivotal role in cell survival.     

Adaptive changes in renal mitochondrial redox status in diabetic nephropathy

Nephropathy is a serious and common complication of diabetes. In the streptozotocin (STZ)-treated rat model of diabetes, nephropathy does not typically develop until 30 to 45 days post-injection, although hyperglycemia occurs within 24 h. We tested the hypothesis that chronic hyperglycemia results in a modest degree of oxidative stress that is accompanied by compensatory changes in certain antioxidants and mitochondrial redox status. We propose that as kidneys progress to a state of diabetic nephropathy, further adaptations occur in mitochondrial redox status. Basic parameters of renal function in vivo and several parameters of mitochondrial function and glutathione (GSH) and redox status in isolated renal cortical mitochondria from STZ-treated and age-matched control rats were examined at 30 days and 90 days post-injection. While there was no effect of diabetes on blood urea nitrogen, measurement of other, more sensitive parameters, such as urinary albumin and protein, and histopathology showed significant and progressive worsening in diabetic rats. Thus, renal function is compromised even prior to the onset of frank nephropathy. Changes in mitochondrial respiration and enzyme activities indicated existence of a hypermetabolic state. Higher mitochondrial GSH content and rates of GSH transport into mitochondria in kidneys from diabetic rats were only partially due to changes in expression of mitochondrial GSH carriers and were mostly due to higher substrate supply. Although there are few clear indicators of oxidative stress, there are several redox changes that occur early and change further as nephropathy progresses, highlighting the complexity of the disease.