Cytochrome c release into cytosol with subsequent caspase activation during warm ischemia in rat liver

The Effect of Antioxidant Added to Preservation Solution on the Protection of Kidneys before Transplantation

Ischemia–reperfusion injury is a key clinical problem of transplantology. Current achievements in optimizing organ rinse solutions and storage techniques have significantly influenced the degree of graft damage and its survival after transplantation. In recent years, intensive research has been carried out to maintain the viability of tissues and organs outside the integral environment of the body. Innovative solutions for improving the biochemical functions of the stored organ have been developed. The article discusses directions for modifying preservation solutions with antioxidants. Clinical and experimental studies aimed at optimizing these fluids, as well as perfusion and organ preservation techniques, are presented.

Effect of chronic alcohol consumption on myocardial apoptosis in the rat model of isoproterenol-induced myocardial injury and investigation on the cardioprotective role of calpain inhibitor 1

We investigated the presence of myocardial apoptosis on isoproterenol (ISO)-induced myocardial injury (MI) after long-term high dose alcohol consumption and examined the antiapoptotic role of calpain inhibitor 1. Male Wistar Albino rats (n = 108) were divided into six groups: Control, alcohol (ethanol was given during 30 days for chronic alcohol consumption), MI (150 mg/kg ISO injection at last two days of alcohol consumption), alcohol + MI, alcohol + MI + calpain inhibitor 1 (10 mg/kg inhibitor was injected at 15 min before ISO injections) and Dimethyl Sulfoxide (DMSO) groups. Biochemical, histological, and morphometric methods determined apoptosis levels in the heart tissue of rats. Cytochrome c, caspase 3, and calpain levels were significantly high in alcohol, MI, and alcohol + MI groups. In contrast, mitochondrial cardiolipin content was found to be low in alcohol, MI, and alcohol + MI groups. These parameters were close to the control group in the therapy group. Histological and morphometric data have supported biochemical results. As a result of our biochemical data, myocardial apoptosis was seen in the alcohol, MI, and especially alcohol after MI groups. Calpain inhibitor 1 reduced apoptotic cell death and prevented myocardial tissue injury in these groups. The efficiency of calpain inhibitor was very marked in MI after long-term high dose alcohol consumption.

Pathophysiological Changes During Ischemia-reperfusion Injury in Rodent Hepatic Steatosis

BACKGROUND/AIM

Ischemia and reperfusion injuries may produce deleterious effects on hepatic tissue after liver surgery and transplantation. The impact of ischemia-reperfusion injury (IRI) on the liver depends on its substrate, the percentage of liver ischemic tissue subjected to IRI and the ischemia time. The consequences of IRI are more evident in pathologic liver substrates, such as steatotic livers. This review is the result of an extended bibliographic PubMed search focused on the last 20 years. It highlights basic differences encountered during IRI in lean and steatotic livers based on studies using rodent experimental models.

CONCLUSION

The main difference in cell death between lean and steatotic livers is the prevalence of apoptosis in the former and necrosis in the latter. There are also major changes in the effect of intracellular mediators, such as TNFα and IL-1β. Further experimental studies are needed in order to increase current knowledge of IRI effects and relevant mechanisms in both lean and steatotic livers, so that new preventive and therapeutic strategies maybe developed.

Hypothermic Maintenance of Hepatocyte Spheroids

Primary hepatocytes form spheroids under some culture conditions. These spheroids exhibit many tissuelike ultrastructures and retain many liver-specific functions over a long period of time. They are attractive for many applications employing liver cells. The ability to maintain their viability and functions at a reduced temperature to allow for transportation to the site of their application will facilitate their use. Furthermore, with their structural and functional similarity, they could possibly be used as a model system for studying various liver ischemias. The effect of hypothermic treatment was assessed by oxygen consumption rate, ATP, H2O2, and caspase 8 content, as well as albumin and urea synthesis, during and posttreatment. No single outcome variable gives a superlative quantification of hypothermic damage. Taken together, the hypothermic treatment can be seen as increasingly damaging as the temperature decreases from 21°C to 15°C and 4°C. The addition of the chemical protectants glutathione, N-acetyl-L-cystein (NAC), and tauroursodeoxycholic acid (TUDCA) decreased the damaging effect of hypothermic treatment. This protection effect was even more profound when spheroids were preincubated with the protectant for 24 h, and was most prominent at 4°C. The viability of the hypothermically treated hepatocyte spheroids was confirmed by laser scanning confocal microscopy. The method reported provides a means of maintaining spheroids' viability and may allow for their distribution to application sites at a distance.

Prenatal alcohol-induced neuroapoptosis in rat brain cerebral cortex: protective effect of folic acid and betaine

PURPOSE

Alcohol consumption in pregnancy may cause fetal alcohol syndrome (FAS) in the infant. This study aims to investigate prenatal alcohol exposure related neuroapoptosis on the cerebral cortex tissues of newborn rats and possible neuroprotective effects of betaine, folic acid, and combined therapy.

METHODS

Pregnant rats were divided into five experimental groups: control, ethanol, ethanol + betaine, ethanol + folic acid, and ethanol + betaine + folic acid combined therapy groups. We measured cytochrome c release, caspase-3, calpain and cathepsin B and L. enzyme activities. In order to observe apoptotic cells in the early stages, TUNEL method was chosen together with histologic methods such as assessing the diameters of the apoptotic cells, their distribution in unit volume and volume proportion of cortical intact neuron nuclei.

RESULTS

Calpain, caspase-3 activities, and cytochrome c levels were significantly increased in alcohol group while cathepsin B and L. activities were also found to be elevated albeit not statistically significant. These increases were significantly reversed by folic acid and betaine + folic acid treatments. While ethanol increased the number of apoptotic cells, this increase was prevented in ethanol + betaine and ethanol + betaine + folic acid groups. Morphometric examination showed that the mean diameter of apoptotic cells was increased with ethanol administration while this increase was reduced by betaine and betaine + folic acid treatments.

CONCLUSION

We observed that ethanol is capable of triggering apoptotic cell death in the newborn rat brains. Furthermore, folic acid, betaine, and combined therapy of these supplements may reduce neuroapoptosis related to prenatal alcohol consumption, and might be effective on preventing fetal alcohol syndrome in infants.

Caspase-Independent Apoptosis Induced by Reperfusion Following Ischemia without Bile Duct Occlusion in Rat Liver

The contribution of caspases to hepatic ischemia/reperfusion (I/R)-induced apoptosis has not been completely understood yet. Several studies have demonstrated increased caspase activity during I/R and the protective effect of caspase inhibitors against I/R injuries. However, reports with opposing results also exist. Herein, we examined the contribution of caspases to the I/R-induced hepatic apoptosis in rats using caspase inhibitors and specific substrates of caspases. Hepatic I/R was induced via a 2-h occlusion of the portal vein and the hepatic artery, without conducting bile duct occlusion. DNA laddering and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate (dUTP) nick end-labeling (TUNEL)-positive cells were increased at 3 h after reperfusion. Pretreatment with caspase inhibitors (Z-Asp-2,6-dichlorobenzoyloxymethylketone (Z-Asp-cmk) 2 or 10 mg/kg intravenously (i.v.), 20 mg/kg intraperitoneally (i.p.), Z-Val-Ala-Asp(OMe)-fluoromethylketone (Z-VAD-fmk) 3 mg/kg i.v.) failed to reduce apoptosis induced by I/R. Interestingly, apoptosis induced by the portal triad (hepatic artery, portal vein, and bile duct) occlusion/reperfusion could be marginally attenuated using Z-Asp-cmk (2 mg/kg i.v.). The cleavage activity for Ac-DEVD-α-(4-methylcoumaryl-7-amide) (MCA), a caspase-3/7/8/9 substrate, was significantly increased by I/R. Conversely, the cleavage activities for Ac-DNLD-MCA and MCA-VDQVDGW[K-DNP]-NH₂, specific substrates for caspase-3 and -7 respectively, were decreased by I/R. Protein expression of the cellular inhibitor of apoptosis protein 2 (c-IAP2), an endogenous caspase inhibitor, was increased by ischemia. Nuclear translocation of the apoptosis-inducing factor (AIF), an initiator protein of caspase-independent apoptosis, was also increased during I/R. These results suggest that caspases are inhibited by c-IAP2 induced during ischemia and that AIF may be involved in initiation of apoptosis induced by hepatic I/R without bile duct occlusion.

Methotrexate treatment provokes apoptosis of proliferating keratinocyte in psoriasis patients

Psoriasis is a chronic inflammatory skin disease characterized by hyper proliferation of keratinocytes. Recent data show that the epidermis thickening in psoriasis may be related to imbalance of homeostasis caused by abnormal apoptotic process. Maintenance of keratinocyte apoptotic process is very important in psoriasis. Methotrexate (MTX) has been used for many years to restore the normal skin in psoriasis condition. However, the exact mechanism of MTX in psoriasis condition is poorly understood. The aim of this study was to examine the role of MTX on keratinocyte apoptosis pathway in psoriasis patients. A total of 58 psoriasis vulgaris patients were recruited for this study. Nonlesional skin biopsies served as control. Skin biopsies of psoriatic patients were collected and analyzed for cytosolic, mitochondria and total cytochrome c by ELISA. Expression of caspase-9, NFκBp65, pAkt1 by western blot, real-time PCR and immunohistochemical analysis of c-FLIP protein was analyzed in nonlesional and lesional skin biopsies before (day 0) and after (at the end of 6 and 12 weeks) MTX treatment. After MTX treatment, a significant increase in cytochrome c was observed when compared with before MTX treatment in psoriasis patients (p < 0.001). Protein and gene expression of cleaved caspase-9 were significantly increased after MTX treatment, whereas the expression of Bcl-xL, c-FLIP, NFκBp65, pAkt1 significantly downregulated after MTX treatment. In conclusion, these results showed that intrinsic apoptotic pathway induced by MTX eventually adds the beneficial therapeutic role of MTX in psoriasis by controlling the acanthosis.

The investigation of the prenatal and postnatal alcohol exposure-induced neurodegeneration in rat brain: protection by betaine and/or omega-3

PURPOSE

We aim to study the effect of neurodegeneration on the brain of rat pups caused by prenatal and postnatal ethanol exposure with modified liquid diet to elucidate protective effects of betaine and omega-3 supplementation. When ethanol is consumed during prenatal and postnatal periods, it may result in fetal alcohol syndrome (FAS) in the offspring.

METHODS

Rats were divided into control, ethanol, ethanol + betaine, ethanol + omega-3, ethanol + omega-3 + betaine groups. The effect of betaine and omega-3 in response to ethanol-induced changes on the brain, by biochemical analyses cytochrome c, caspase-3, calpain, cathepsin B and L, DNA fragmentation, histological and morfometric methods were evaluated.

RESULTS

Caspase-3, calpain, cathepsin B, and cytochrome c levels in ethanol group were significantly higher than control. Caspase-3, calpain levels were decreased in ethanol + betaine, ethanol + omega-3, and ethanol + omega-3 + betaine groups compared to ethanol group. Cathepsin B in ethanol + omega-3 + betaine group was decreased compared to ethanol, ethanol + betaine groups. Cathepsin L and DNA fragmentation were found not statistically significant. We found similar results in histological and morfometric parameters.

CONCLUSION

We found that pre- and postnatal ethanol exposure is capable of triggering necrotic cell death in rat brains, omega-3, and betaine reduce neurodegeneration. Omega-3 and betaine may prove beneficial for neurodegeneration, particularly in preventing FAS.

Carbon dioxide‑pneumoperitoneum in rats reduces ischemia/reperfusion‑induced hepatic apoptosis and inflammatory responses by stimulating sensory neurons

Laparoscopic surgery induces a milder inflammatory response than open surgery, however, the precise mechanisms underlying this phenomenon remain to be elucidated. Our previous study demonstrated that stimulation of sensory neurons inhibited hepatic apoptosis and inflammatory responses in rats subjected to hepatic ischemia/reperfusion (I/R). Since carbon dioxide (CO2) has been demonstrated to stimulate sensory neurons, it was hypothesized that CO2‑pneumoperitoneum, as used in laparoscopic surgery, may attenuate inflammatory responses by stimulating sensory neurons. This hypothesis was examined using rats subjected to hepatic I/R. The rats were subjected to partial hepatic ischemia for 60 min followed by reperfusion. Abdominal insufflation with CO2 or air was performed for 30 min prior to hepatic I/R. Hepatic I/R‑induced hepatocellular apoptosis and expression of the neutrophil chemoattractant endothelial monocyte‑activated polypeptide‑II, were inhibited by CO2‑pneumoperitoneum, however, not by air‑pneumoperitoneum. Pretreatment with the transient receptor potential vanilloid 1 antagonist SB366791 reversed the protective effects of CO2‑pneumoperitoneum. The results from the present study demonstrated that CO2‑pneumoperitoneum attenuates hepatic apoptosis and inflammatory responses in rats subjected to hepatic I/R, possibly by stimulating sensory neurons. These findings suggested that CO2‑pneumoperitoneum contributed to the attenuated inflammatory response observed following laparoscopic surgery.

Oxymatrine induces mitochondria dependent apoptosis in human osteosarcoma MNNG/HOS cells through inhibition of PI3K/Akt pathway

The cytostatic drug from traditional Chinese medicinal herb has acted as a chemotherapeutic agent used in treatment of a wide variety of cancers. Oxymatrine, classified as a quinolizidine alkaloid, is a phytochemical product derived from Sophora flavescens, and has been reported to possess anticancer activities. However, the cancer growth inhibitory effects and molecular mechanisms in human osteosarcoma MNNG/HOS cell have not been well studied. In the present study, the cytotoxic effects of oxymatrine on MNNG/HOS cells were examined by MTT and bromodeoxyuridine (BrdU) incorporation assays. The percentage of apoptotic cells and the level of mitochondrial membrane potential (Δψ m) were assayed by flow cytometry. The levels of apoptosis-related proteins were measured by Western blot analysis or enzyme assay Kit. Our results showed that treatment with oxymatrine resulted in a significant inhibition of cell proliferation and DNA synthesis in a dose-dependent manner, which has been attributed to apoptosis. Furthermore, we found that oxymatrine considerably inhibited the expression of Bcl-2 whilst increasing that of Bax. This promoted mitochondrial dysfunction, leading to the release of cytochrome c from the mitochondria to the cytoplasm, as well as the activation of caspase-9 and -3. Moreover, addition of oxymatrine to MNNG/HOS cells also attenuated phosphatidylinositol 3-kinase (PI3K) ⁄Akt signaling pathway cascade, evidenced by the dephosphorylation of P13K and Akt. Likewise, oxymatrine significantly suppressed tumor growth in female BALB/C nude mice bearing MNNG/HOS xenograft tumors. In addition, no evidence of drug-related toxicity was identified in the treated animals by comparing the body weight increase and mortality. Therefore, these findings should be useful for understanding the apoptotic cellular mechanism mediated by oxymatrine and might offer a therapeutic potential advantage for human osteosarcoma chemoprevention or chemotherapy.

Activation of caspase-9 and its influencing factors in beef during conditioning

To study the activation of caspase-9 and its potential influence in conditioning, longissimus thoracis (LT), semitendinosus (STN) and psoas minor (PMi) muscles were used to analyze the ratio of pro-apoptotic bax to anti-apoptotic bcl-2 in fresh tissues and observe the changes in ATP, cytosolic cytochrome c and caspase-9 activity levels during storage at 4°C. Caspase-9 activity at 5 h is higher than the activity at 0 and 24 h in the muscles (P<0.001). The ATP content decreased between 0 and 3 h, between 8 and 14 h in the PMi and LT muscles (P<0.0001), whereas between 0 and 5 h, between 8 and 14 h in the STN muscle (P<0.0001). There is 60.2%, 55.3% and 43.1% available ATP in the STN, LT and PMi muscles at 5 h, respectively. The cytosolic cytochrome c level increased during 5 and 24 h storage in the LT and PMi muscles (P<0.0001), during 5 and 96 h in the STN muscle (P<0.0001). The cytosolic cytochrome c at 24 h (P<0.001) and ratio of bax to bcl-2 (P<0.05) was higher in the PMi than in other muscles. We concluded that the increase in cytosolic cytochrome c and available intracellular ATP should be responsible for the increase in caspase-9 activity; the activation of caspase-9 could be limited by the subsequent depletion of ATP; the postmortem release level of cytochrome c could be determined by the ratio of bax to bcl-2 in fresh tissues.

DNase γ is the effector endonuclease for internucleosomal DNA fragmentation in necrosis

Apoptosis and necrosis, two major forms of cell death, can be distinguished morphologically and biochemically. Internucleosomal DNA fragmentation (INDF) is a biochemical hallmark of apoptosis, and caspase-activated DNase (CAD), also known as DNA fragmentation factor 40 kDa (DFF40), is one of the major effector endonucleases. DNase γ, a Mg(2+)/Ca(2+)-dependent endonuclease, is also known to generate INDF but its role among other apoptosis-associated endonucleases in cell death is unclear. Here we show that (i) INDF occurs even during necrosis in cell lines, primary cells, and in tissues of mice in vivo, and (ii) DNase γ, but not CAD, is the effector endonuclease for INDF in cells undergoing necrosis. These results document a previously unappreciated role for INDF in necrosis and define its molecular basis.

In the eye of the storm: mitochondrial damage during heart and brain ischaemia

We review research investigating mitochondrial damage during heart and brain ischaemia, focusing on the mechanisms and consequences of ischaemia-induced and/or reperfusion-induced: (a) inhibition of mitochondrial respiratory complex I; (b) release of cytochrome c from mitochondria; (c) changes to mitochondrial phospholipids; and (d) nitric oxide inhibition of mitochondria. Heart ischaemia causes inhibition of cytochrome oxidase and complex I, release of cytochrome c, and induction of permeability transition and hydrolysis and oxidation of mitochondrial phospholipids, but some of the mechanisms are unclear. Brain ischaemia causes inhibition of complexes I and IV, but other effects are less clear.

Daphnoretin induces cell cycle arrest and apoptosis in human osteosarcoma (HOS) cells

In this study antiproliferation, cell cycle arrest and apoptosis induced by daphnoretin in human osteosarcoma (HOS) cells were investigated. Antiproliferative activity was measured with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The IC(50) value of daphnoretin was 3.89 μM after 72 h treatment. Induction of apoptosis was evidenced by apoptotic body appearance and Annexin V-FITC/PI apoptosis detection kit. Flow cytometric analysis indicated daphnoretin arrested the cell cycle in the G2/M phase. Western-blot assay showed that the G2/M phase arrest was accompanied by down-regulation of cdc2, cyclin A and cyclin B1. Moreover, daphnoretin inhibited Bcl-2 expression and induced Bax expression to desintegrate the outer mitochondrial membrane and causing cytochrome c release. Mitochondrial cytochrome c release was associated with the activation of caspase-9 and caspase-3 cascade. Our results demonstrated that daphnoretin caused death of HOS cells by blocking cells successively in G2/M phases and activating the caspase-3 pathway.

Hepatocyte apoptosis is enhanced after ischemia/reperfusion in the steatotic liver

Liver steatosis is associated with organ dysfunction after hepatic resection and transplantation which may be caused by hepatic ischemia/reperfusion injury. The aim of the current study was to determine the precise mechanism leading to hepatocyte apoptosis after steatotic liver ischemia/reperfusion. Using a murine model of partial hepatic ischemia for 90 min, we examined the levels and pathway of apoptosis, and the peroxynitrite expression, serum alanine aminotransferase levels, and liver histology 1 and 4 h after reperfusion. In the steatotic liver, the peroxynitrite expression increased after ischemia/reperfusion. Significant hepatocyte apoptosis in the steatotic liver was seen after reperfusion, caused by upregulation of cleaved caspases 9 and 3, but not caspase 8. Serum alanine aminotransferase levels were elevated and histological examination revealed severe liver injury in the steatotic liver 4 h after reperfusion. In mice treated with aminoguanidine, ischemia/reperfusion-induced increases in serum alanine aminotransferase levels and apoptosis were significantly reduced in steatotic liver compared with mice treated with phosphate buffered saline. Survival of mice with steatotic livers significantly improved by treatment with aminoguanidine. Our data suggested that the steatotic liver is vulnerable to hepatic ischemia/reperfusion, leading to significant hepatocyte apoptosis by the mitochondrial permeability transition, and thereby resulting in organ dysfunction.

Intracellular oxygenation and cytochrome oxidase C activity in ischemic preconditioning of steatotic rabbit liver

BACKGROUND

Mild to moderate steatotic livers are used as marginal donors in liver transplantation. Very little is known about the mechanisms of ischemia reperfusion (IR) injury (IRI) in fatty liver. This study aimed to establish whether cytochrome oxidase C (COX) activity is compromised by IRI in fatty liver and whether ischemic preconditioning (IPC) can protect COX activity.

METHODS

New Zealand rabbits were fed on a high-cholesterol diet for 8 weeks to induce moderate hepatic steatosis. Three groups were tested. The IR group underwent 60 minutes of ischemia, followed by 7 hours of reperfusion. The IPC group (IPC + IR) underwent 5 minutes of ischemia, followed by 10 minutes of reperfusion and then 60 minutes of ischemia and 7 hours of reperfusion. The control group (sham) underwent the same surgical procedure, but ischemia was not induced. Deoxyhemoglobin, oxyhemoglobin, and change in the redox state of COX was continuously monitored in vivo by near-infrared spectroscopy. COX and citrate synthase (CS) activity assays were carried out on liver biopsy specimens in vitro. Bile was collected continuously during the procedure and analyzed using proton nuclear magnetic resonance spectroscopy.

RESULTS

The IR group had decreased COX activity and tissue oxygenation represented by deoxyhemoglobin, oxyhemoglobin, COX, and elevated redox ratios of lactate/pyruvate and β-hydroxybutarate/acetoacetate in vivo and a decrease in COX and CS activity in vitro. The IPC + IR group showed higher levels of all measured parameters in vivo and showed a smaller decrease in COX and CS activity in vitro.

CONCLUSION

This study shows that IRI affects COX activity in fatty livers. This is attenuated by IPC.

Effect of caspase inhibition on thymic apoptosis in hemorrhagic shock

In hemorrhagic shock (HS) an increased thymic apoptosis (TA) was described. The aim of this study was to evaluate the effect of administration of the caspase inhibitor N-benzyloxy-carbonil-Val-Ala-Asp-fluoromethylketone (Z-VAD-FMK) during the resuscitation phase on TA, organ dysfunctions, and tumor necrosis factor (TNF)-alpha release in HS. Forty rats were randomly assigned to four groups: no HS/resuscitation (sham); HS/resuscitation with shed blood and normal saline (control); HS/resuscitation with shed blood and phosphate-buffered solution (PBS) (vehicle); and HS/resuscitation with shed blood and Z-VAD-FMK (inhibitor). Rats were subjected to HS by blood removal to a MAP of 35-40 mmHg. After a 1-h shock period, the animals were resuscitated according to the protocol. At 1 and 3 h after resuscitation, transaminases, creatinine, urea, lipase, TNF-alpha, and TA were evaluated. Our study showed that a nonlethal HS is early able to induce organ dysfunctions and increased TA. Administration of Z-VAD-FMK did not significantly decrease organ dysfunctions, while it induced a significant TNF-alpha release. TA was significantly reduced by Z-VAD-FMK after 1 h, but not after 3 h. Our results suggest that postinjury caspase inhibition does not attenuate organ dysfunctions, and also does not permanently reduce TA induced by HS and resuscitation in rats.

Apoptotic signaling induces hyperpermeability following hemorrhagic shock

Hemorrhagic shock (HS) disrupts the endothelial cell barrier, resulting in microvascular hyperpermeability. Recent studies have also demonstrated that activation of the apoptotic signaling cascade is involved in endothelial dysfunction, which may result in hyperpermeability. Here we report involvement of the mitochondrial "intrinsic" pathway in microvascular hyperpermeability following HS in rats. HS resulted in the activation of the mitochondrial intrinsic pathway, as is evident from an increase in the proapoptotic Bcl-2 family member BAK, release of mitochondrial cytochrome c into the cytoplasm, and activation of caspase-3. This, along with the in vivo transfection of the proapoptotic peptide BAK (BH3), resulted in hyperpermeability (as visualized by intravital microscopy), release of mitochondrial cytochrome c into the cytoplasm, and activation of caspase-3. Conversely, transfection of the BAK (BH3) mutant had no effect on hyperpermeability. Together, these results demonstrate involvement of the mitochondrial intrinsic apoptotic pathway in HS-induced hyperpermeability and that the attenuation of this pathway may provide an alternative strategy in preserving vascular barrier integrity.

Cell suicide and caspases

Programmed cell death or apoptosis is a well regulated physiological form of cellular autodestruction. It plays an essential role in embryonic development, homeostasis, remodeling, surveillance, and host defense mechanisms. Conversely dysregulation of apoptosis, resulting in either too less or excessive cell death is implicated in pathogenesis of stroke, myocardial infarction, neurodegenerative diseases, cancer and autoimmmune disorders. Apoptosis is coordinated by a family of cysteine proteinases called caspases, which dismantle the cell by targeting panoply of proteins. The mammalian caspase family contains 14 members, a subset participates in cellular demise and the remaining are involved in the processing of pro-inflammatory cytokines. We have tried to develop a simplified picture of basic apoptotic mechanisms on the basis of recent insights into the area.

Intralipid minimizes hepatocytes injury after anoxia-reoxygenation in an ex vivo rat liver model

OBJECTIVE

Ischemia-reperfusion injury is a determinant in liver injury occurring during surgical procedures, ischemic states, and multiple organ failure. The pre-existing nutritional status of the liver, i.e., fasting, might contribute to the extent of tissue injury. This study investigated whether Intralipid, a solution containing soybean oil, egg phospholipids, and glycerol, could protect ex vivo perfused livers of fasting rats from anoxia-reoxygenation injury.

METHODS

The portal vein was cannulated, and the liver was removed and perfused in a closed ex vivo system. Isolated livers were perfused with glucose 5.5 and 15 mM, and two different concentrations of Intralipid, i.e., 0.5:100 and 1:100 (v/v) Intralipid 10%:medium (n = 5 in each group). The experiment consisted of perfusion for 15 min, warm anoxia for 60 min, and reoxygenation during 60 min. Hepatic enzymes, potassium, glucose, lactate, bilirubin, dienes, trienes, and cytochrome-c were analyzed in perfusate samples. The proportion of glycogen in hepatocytes was determined in biopsies.

RESULTS

Intralipid attenuated transaminases, lactate dehydrogenase, potassium, diene, and triene release in the perfusate (dose-dependant) during the reoxygenation phase when compared with glucose-treated groups. The concentration of cytochrome-c in the medium was the highest in the 5.5-mM glucose group. The glycogen content was low in all livers at the start of the experiment.

CONCLUSION

Intralipid presents, under the present experimental conditions, a better protective effect than glucose in anoxia-reoxygenation injury of the rat liver.

Reduction of ischemia reperfusion injury after liver resection and hepatic inflow occlusion by α-lipoic acid in humans

AIM: To evaluate the protective effects of preconditioning by α-lipoic acid (LA) in patients undergoing hepatic resection under inflow occlusion of the liver.

METHODS: Twenty-four patients undergoing liver resection for various reasons either received 600 mg LA or NaCl 15 min before transection performed under inflow occlusion of the liver. Blood samples and liver wedge biopsy samples were obtained after opening of the abdomen immediately after inflow occlusion of the liver, and 30 min after the end of inflow occlusion of the liver.

RESULTS: Serum levels of aspartate transferase and alanine transferase were reduced at all time points in patients who received LA in comparison to those who received NaCL. This was accompanied by reduced histomorphological features of oncosis. We observed TUNEL-positive hepatocytes in the livers of the untreated patients, especially after 30 min of ischemia. LA attenuated this increase of TUNEL-positive hepatocytes. Under preconditioning with LA, ATP content was significantly enhanced after 30 min of ischemia and after 30 min of reperfusion.

CONCLUSION: This is the first report on the potential for LA reducing ischemia/reperfusion injury (IRI) of the liver in humans who were undergoing liver surgery. Beside its simple and rapid application, side effects did not occur. LA might therefore represent a new strategy against hepatic IRI in humans.

Different protection mechanisms after pretreatment with glycine or alpha-lipoic acid in a rat model of warm hepatic ischemia

BACKGROUND/AIM

Alpha-lipoic (LA) acid pretreatment has previously been described to reduce ischemia/reperfusion injury (IRI) after warm liver ischemia, whereas glycine pretreatment has been shown to be protective mostly in models of cold hepatic ischemia. The aim of this study was to determine whether glycine decreases IRI after warm hepatic ischemia. Furthermore we investigated whether doses of LA other than those used previously are also protective against IRI after warm hepatic ischemia.

METHODS

Selective liver ischemia was maintained over a period of 90 min. In long-term as well as short-term experiments we studied IRI in several groups comparing animal survival as the pivotal endpoint.

RESULTS

Animal survival was improved by glycine and 5,000 micromol LA, whereas all animals died within 3 days after pretreatment with 50 micromol LA. In the glycine group we observed a tendency towards decreased apoptosis-related cell death measured by the activity of caspase-3 in liver tissue and the percentage of TUNEL-positive hepatocytes in comparison to the untreated group. Serum alpha-glutathione S-transferase, lipid peroxidation, and caspase-3 activity as well as the percentage of TUNEL-positive hepatocytes and the percentage of liver necrosis were only significantly decreased by 5,000 micromol LA pretreatment. Liver tissue levels of tumor necrosis factor (TNF)alpha were reduced only in the glycine group whereas TNFalpha was increased in the untreated as well as the LA group. Levels of TNFalpha mRNA were upregulated in both the glycine- and LA-pretreated groups.

CONCLUSION

Our data show that increased animal survival by glycine was accompanied by a reduced TNFalpha content in liver tissue. Protection by glycine is likely to result from a reduction in adverse TNFalpha effects. Administration of high-dose LA on the other hand led to a significant reduction in necrosis- and apoptosis-related cell death in IRI of the liver without a reduction in liver TNFalpha.

Ca(2+) rise within a narrow window of concentration prevents functional injury of mitochondria exposed to hypoxia/reoxygenation by increasing antioxidative defence

Injury of liver by ischaemia crucially involves mitochondrial damage. The role of Ca(2+) in mitochondrial damage is still unclear. We investigated the effect of low micromolar Ca(2+) concentrations on respiration, membrane permeability, and antioxidative defence in liver mitochondria exposed to hypoxia/reoxygenation. Hypoxia/reoxygenation caused decrease in state 3 respiration and in the respiratory control ratio. Liver mitochondria were almost completely protected at about 2 microM Ca(2+). Below and above 2 microM Ca(2+), mitochondrial function was deteriorated, as indicated by the decrease in respiratory control ratio. Above 2 microM Ca(2+), the mitochondrial membrane was permeabilized, as demonstrated by the sensitivity of state 3 respiration to NADH. Below 2 microM Ca(2+), the nitric oxide synthase inhibitor nitro-l-arginine methylester had a protective effect. The activities of the manganese superoxide dismutase and glutathione peroxidase after hypoxia showed maximal values at about 2 microM Ca(2+). We conclude that Ca(2+) exerts a protective effect on mitochondria within a narrow concentration window, by increasing the antioxidative defence.

Expression of Fas ligand by hepatic macrophages in patients with fulminant hepatic failure

OBJECTIVES

The mechanisms of Fas-Fas ligand (Fas-FasL)-mediated apoptosis in the pathogenesis of fulminant hepatic failure (FHF) have not been well defined. This clinical study was carried out to assess which cells expressed Fas-FasL and to determine their involvement.

METHODS

The subjects were 24 patients with FHF who underwent liver transplantation at our institution. For comparison, nine chronic hepatitis (CH) patients and six living liver donors (LD) were also enrolled. Liver tissues were obtained for histological (hematoxylin-eosin, terminal deoxynucleotidyl transferase [TdT]-mediated dUTP-biotin nick-end labeling [TUNEL], immunohistochemistry, and double immunofluorescence staining) and reverse transcription PCR (RT-PCR; cytokines and chemokines) analysis.

RESULTS

The numbers of TUNEL-, FasL-, and CD68-positive cells in the livers of patients with FHF were significantly larger than in those with CH or with normal livers. Double immunofluorescence staining showed that FasL was expressed predominantly on liver macrophages and rarely on CD8-positive lymphocytes. RT-PCR study showed increased expression of FasL; interferon-gamma; interleukin-18; macrophage inhibitory protein-1beta; and regulated upon activation, normal T cell expressed and secreted in the livers of patients with FHF compared with those of LD.

CONCLUSIONS

Macrophages and their expression of FasL may play roles in the pathogenesis of FHF.

MCI-186 (edaravone), a free radical scavenger, attenuates hepatic warm ischemia-reperfusion injury in rats

Hepatic warm ischemia-reperfusion injury (IRI) during hepatectomy and liver transplantation is a major cause of liver dysfunction in which the pathologic role of free radicals is a major concern. To assess the effect of MCI-186 (edaravone) on hepatic IRI, male Wistar rats were subjected to partial hepatic ischemia for 60 min after pretreatment with vehicle (group C) or MCI-186 (group M), or after both MCI-186 pretreatment and additional administration of MCI-186 12 h after reperfusion (group MX). Groups M and MX showed significantly lower levels of serum alanine aminotransferase and hepatic lipid peroxidation than group C, and also significantly lower expression levels of mRNA for cytokines, chemokines and intercellular adhesion molecule-1. There were fewer tissue monocytes and neutrophils in groups M and MX than in group C. These effects were more marked in group MX than in group M. Our findings suggest that treatment with MCI-186 attenuates hepatic IRI in this rat in vivo model.

Isoflurane preconditioning protects against ischemia-reperfusion injury partly by attenuating cytochrome c release from subsarcolemmal mitochondria in isolated rat hearts

AIM

To examine if isoflurane preconditioning can attenuate ischemia/reperfusion injury by reducing cytochrome c release from inner mitochondrial membrane.

METHODS

Isolated hearts of Sprague-Dawley rats were perfused on Langendorff apparatus. Hearts were randomly assigned to a non-treated group (CON group, n=12) or three isoflurane preconditioning groups (0.5% ISC group, 1.0% ISC group, and 2.0% ISC group; n=12). In the latter three groups, isoflurane was given at concentrations of 0.5%, 1.0%, and 2.0% for 15 min with 15-min washout before 30-min ischemia. Subsarcolemmal mitochondria of the myocardium were isolated after 60-min reperfusion. Hemodynamics of the each heart was recorded, infarct size of the hearts and contents of cytosolic cytochrome or mitochondrial cytochrome c were measured at the end of reperfusion. Morphology of isolated mitochondria in the four groups was evaluated, respectively.

RESULTS

Compared with the CON group, cytosolic cytochrome c in 0.5% ISC group, 1.0% ISC group, and 2.0% ISC group were significantly decreased along with a significant increase of mitochondrial cytochrome c. Infarct size of the hearts in the four groups were 56%+/-12%, 41%+/-12%, 32%+/-7% and 33%+/-11%, respectively. The values of the three isoflurane preconditioning groups were significantly lower than that of the CON group (P<0.05). Isoflurane exposure before ischemia can attenuate the change of morphology of mitochondria after reperfusion. The effects of 2.0% isoflurane on reducing cytochrome c release were more remarkable than 0.5% and 1.0% concentrations of isoflurane.

CONCLUSION

Myocardioprotective effects of isoflurane preconditioning were associated with attenuation of cytochrome c loss from the inner membrane of subsarcolemmal mitochondria.

Sustaining a Bioartificial Liver under Hypothermic Conditions

Bioartificial liver (BAL) devices employing xenogeneic hepatocytes are being developed as a temporary support of liver failure. For clinical applications, transporting such a device from the manufacturing site to the hospital is necessary. We investigated the effect of hypothermic treatment on the performance of the collagen-entrapment BAL device developed at the University of Minnesota. A number of chemical protectants were examined for their effectiveness in minimizing damage to hepatocytes. Preincubation with protectant (tauroursodeoxycholic acid, TUDCA) before hypothermic treatment improved posttreatment BAL performance. Oxygen consumption and albumin and urea synthesis all resumed at levels comparable to pretreatment levels. The method described will facilitate the application of BAL in the treatment of liver failure.

Role of the permeability transition pore in cytochrome C release from mitochondria during ischemia-reperfusion in rat liver

Ischemia and reperfusion cause mitochondrial dysfunctions that initiate the mitochondrial apoptosis pathway. They involve the release of cytochrome C and the activation of the caspase cascade but the mechanism(s) leading to cytochrome C release is(are) poorly understood. The aim of this study was to analyse the relation between cytochrome C release and the opening of the permeability transition pore (PTP) during in situ liver ischemia and reperfusion. Liver ischemia was induced for 30, 60 and 120 min and blood re-flow was subsequently restored for 30 and 180 min. Ischemia hugely altered mitochondrial functions, i.e., oxidative phosphorylation and membrane potential, and was accompanied by a time-dependent mitochondrial release of cytochrome C into the cytosol and by activations of caspases-3 and -9. PTP opening was not observed during ischemia, as demonstrated by the absence of effect of an in vivo pre-treatment of rats with cyclosporin A (CsA), a potent PTP inhibitor. Cytochrome C release was due neither to a direct effect of caspases onto mitochondria nor to an interaction of Bax or Bid with the mitochondrial membrane but could be related to a direct effect of oxygen deprivation. In contrast, during reperfusion, CsA pre-treatment inhibits cytochrome C release, PTP opening and caspase activation. At this step, cytochrome C release is likely to occur as a consequence of PTP opening. In conclusion, our study reveals that cytochrome C release, and thus the induction of the mitochondrial cell death pathway, occur successively independently and dependent on PTP opening during liver ischemia and reperfusion, respectively.

Apoptotic cell death is initiated during normothermic ischemia in human kidneys

Ischemic damage plays an important role in post-transplant organ failure. Activation of the apoptotic cascade is crucially involved in post-ischemic inflammation resulting in tissue damage and organ dysfunction. Here we investigate the initiation of the apoptotic cascade during normothermic ischemia in human kidneys using a model for normothermic ischemia with kidneys nephrectomized because of renal cell carcinoma. Ex vivo, kidneys were stored at 37 degrees C, and consecutive biopsies were taken from disease-free tissue. Pro- and anti-apoptotic proteins were assessed by Western blotting and immunofluorescence. During normothermic ischemia the pro-apoptotic proteins Bax and activated caspase-9 increased with ischemia time, whereas caspase-8 was not activated. The anti-apoptotic proteins Bcl-2 and cFLIP decreased in time. Data on Bcl-2 and Bax were supported by immunofluorescence for Bcl-2 and activated Bax. However, activation of the central effector caspase-3, essential for execution of the apoptotic process, was not detected. In conclusion, during normothermic ischemia the apoptotic cascade in the human kidney is initiated, but not fulfilled. Our data show that the duration of ischemia significantly correlates with activation of the apoptotic cascade. These findings provide insight in the initiation of apoptotic cell-death during warm ischemia and may be useful in the assessment of ischemic injury.

Dynamic movement of cytochrome c from mitochondria into cytosol and peripheral circulation in massive hepatic cell injury

BACKGROUND

In the process of apoptosis, it is known that the transition of cytochrome c from mitochondria into the cytosol occurs, and tumor necrosis factor (TNF)-alpha is one of the molecules responsible for this event. But in the state of hypercytokine induced by D-galactosamine (D-GaIN)/Lipopolysaccharide (LPS), the localization of cytochrome c is little known.

METHODS

Rats were administrated with D-GaIN(700 mg/kg)/LPS(200 microg/kg). Blood and tissue samples were collected and examined for levels of pro-inflammatory cytokines, the apoptosis of liver cells, and the localization of cytochrome c.

RESULT

Before administration of D-GaIN/LPS, cytochrome c was definitely localized in the mitochondria. At 2 h after simultaneous administration of D-GaIN/LPS, cytochrome c had accumulated in the cytosol following abrupt increases of plasma TNF-alpha. Massive cell destruction due to apoptosis proved by Terminal deoxynucleo-tidyl transferase-mediated dUTP nick end labeling staining was observed in liver tissue 4 h later and markedly increased levels of cytochrome c were detected in the plasma 12 h after D-GaIN/LPS administration.

CONCLUSION

Liver injury induced by simultaneous administration of D-GaIN/LPS was closely associated with the production of TNF-alpha, and also with the dynamic movement of cytochrome c from the mitochondria into the cytosol, and then into the systemic circulation. The detection of plasma cytochrome c levels may be a useful clinical tool for the detection of apoptosis in vivo.

Akt activation protects rat liver from ischemia/reperfusion injury1

BACKGROUND

Apoptosis as well as necrosis may play an important role in hepatic ischemia/reperfusion (I/R) injury. Akt, a serine-threonine protein kinase, is known to promote cell survival. We investigated whether gene transfer of constitutively active or dominant negative Akt could affect hepatic I/R injury.

MATERIALS AND METHODS

Hepatic I/R injury was induced in rats by Pringle's maneuver for 20 min followed by reperfusion. Adenoviruses encoding a constitutively active form of Akt (myrAkt), a dominant negative form of Akt (dnAkt), or beta-galactosidase (LacZ) were injected through the tail vein 72 h before hepatic I/R.

RESULTS

Terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling (TUNEL) staining demonstrated a significant increase in the positive cells 240 min after reperfusion. Immunoblotting with phospho-Akt antibody showed phosphorylation of Akt from 90 to 180 min after reperfusion. The expression of myrAkt reduced the number of TUNEL-positive cells and hepatic necrosis around the central veins in the liver after reperfusion. This expression also significantly inhibited the increase in serum alanine aminotransferase (297 +/- 131 IU/L, P < 0.05) 120 min after I/R, compared with increases in uninfected (1761 +/- 671 IU/L), LacZ adenovirus (1528 +/- 671 IU/L)-, and dnAkt adenovirus (1342 +/- 485 IU/L)-infected rats. MyrAkt expression phosphorylated Bad and inhibited the release of cytochrome-c after reperfusion. No difference in nuclear translocation of nuclear factor (NF)-kappaB, p65 was seen among the three groups of rats, however.

CONCLUSION

Adenoviral gene transfer of myrAkt could inhibit apoptotic cell death and subsequent hepatic I/R injury in the rat, through Bad, not NF-kappaB.

Induction of apoptosis by 2,3,7,8-tetrachlorodibenzo-p-dioxin following endotoxin exposure

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a potent and persistent environmental toxin that induces hepatotoxicity and increases endotoxin-induced liver injury. The objective of this study was to evaluate whether TCDD could modulate apoptosis and cytokine-controlled apoptotic signaling pathways following lipopolysaccharide (LPS) exposure in female B6C3F1 mice. The effects of TCDD treatment were most dramatic late in the time course (10-14 days posttreatment). Serum enzyme activities were elevated at day 10 (100 microg TCDD/40 microg LPS treatment) and day 14 (100 microg TCDD/saline treatment), indicating peak liver damage occurred at those times. Histological examination of perfused livers showed an increase in apoptotic cells at day 14 in animals treated with 10 microg TCDD. Caspase-1 activity was suppressed at 14 days in mice treated with 100 microg TCDD/40 microg LPS and 100 microg TCDD/4 microg LPS compared to the respective corn oil (CO)/LPS-treated controls. Caspase-3 activity was suppressed at 14 days in 100 microg TCDD/saline-100 microg TCDD/40 microg LPS- and 100 microg TCDD/4 microg LPS-treated mice compared to respective CO/saline- or CO/LPS-treated control mice. At 40 microg LPS, caspase activity was stimulated in TCDD (100 microg)-exposed mice at 3 and 7 days and then suppressed at 10 and 14 days. Western blot analysis, electrophoretic mobility shift assay, and ELISA did not show any effect by TCDD (100 microg) on IkappaB-beta and IkappaB-alpha protein expression or on DNA binding activity of the nuclear NFkappaB protein. These data indicate that TCDD induces apoptosis 14 days posttreatment; however, we found no evidence of suppression of the antiapoptotic transcription factor NFkappaB.

The caspase inhibitor IDN-6556 prevents caspase activation and apoptosis in sinusoidal endothelial cells during liver preservation injury

Cold ischemia (CI)-warm reperfusion (WR) liver injury remains a problem in liver transplantation. CI-WR initially causes sinusoidal endothelial cell (SEC) apoptosis through a caspase-dependent mechanism. We previously showed that the caspase inhibitor IDN-1965 prevents CI-WR-induced SEC apoptosis. However, this agent required to be administered to the donor, preservation solution, and recipient for efficacy. Here, we show that a second-generation caspase inhibitor, IDN-6556, effectively prevents CI-WR-induced SEC injury when added only to University of Wisconsin (UW) cold storage media. Rat livers were stored in UW solution for 24 hours at 4 degrees C and reperfused for 1 hour at 37 degrees C. Apoptosis was quantitated using terminal deoxynucleotide transferasemediated deoxyuridine triphosphate nick end labeling (TUNEL) assay and caspase 3 activation determined by biochemical measurement and immunohistochemical analysis. Pan-caspase inhibitors (IDN-8066, IDN-7503, IDN-7436, IDN-1965, and IDN-6556) were applied at preischemic, cold preservation, or reperfusion periods. TUNEL-positive SEC and caspase 3-like activity in the liver was increased by CI-WR. Three caspase inhibitors (IDN-8066, IDN-1965, and IDN-6556) effectively attenuated SEC apoptosis and caspase 3 activation. The most potent inhibitor, IDN-6556, reduced SEC apoptosis and caspase 3 activity by 55% and 94%, respectively. Prevention of SEC apoptosis by IDN-6556 was not reduced when this agent was administered only during the cold preservation period. When added to the preservation solution, the caspase inhibitor IDN-6556 appears to be a feasible therapeutic agent against ischemia-reperfusion injury in liver transplantation.

Ischemic preconditioning attenuates the oxidant-dependent mechanisms of reperfusion cell damage and death in rat liver

In an in vivo rat model of liver ischemia followed by reperfusion a consistent appearance of necrosis and activation of biochemical pathways of apoptosis was reproduced and monitored after 30 minutes reperfusion. Preconditioning by application of a short cycle of ischemia-reperfusion (10 minutes + 10 minutes) positively conditioned recovery of the organ at reperfusion, attenuating both necrotic and apoptotic events. Preconditioning at least halved cell oxidative damage occurring early at reperfusion, and as a major consequence, the increase of cytolysis and apoptosis occurring at reperfusion was about 50% less. The attenuation of both pathways of cell death by preconditioning appeared at least partly related to its modulate action on H(2)O(2) and 4-hydroxy-2,3-trans-nonenal production. The overall data point to a marked diminished oxidant generation and oxidative reactions as one major possible mechanism through which ischemic preconditioning exerts protection against necrotic and apoptotic insult to the postischemic liver.