The effect of Z-FA.FMK on D-galactosamine/TNF-alpha-induced liver injury in mice

Microcirculatory disturbance in acute liver injury

Microcirculatory disturbance is thought to be involved in the pathogenesis of acute liver injury (ALI). The current study examined the pathophysiologic role of hepatic microcirculatory disturbance in patients with ALI and in mouse models of ALI. Using serum aminotransferase (ALT)/lactate dehydrogenase (LDH) ratio as a hypoxic marker, 279 patients with ALI were classified into the low ALT/LDH ratio (ALT/LDH ≤1.5) and high ALT/LDH ratio group (ALT/LDH >1.5). In the low ALT/LDH ratio group, serum ALT, LDH, fibrinogen degradation products and prothrombin time-international normalized ratio were increased relative to the high ALT/LDH ratio group. Histologically, hepatic expression of tissue factor (TF) and hypoxia-related proteins was enhanced in the low ALT/LDH ratio group, and this was accompanied by sinusoidal fibrin deposition. Sinusoidal hypercoagulation and intrahepatic hypoxia was also analyzed in two different mouse models of ALI; Concanavalin A (ConA) mice and Galactosamine/tumor necrosis factor (TNF)-α (G/T) mice. Serum ALT/LDH ratio in ConA mice was significantly lower compared with G/T mice. Pimonidazole staining revealed the upregulation of hypoxia-related proteins in ConA mice. Recombinant human soluble thrombomodulin improved liver damage in ConA mice in association with reduced sinusoidal hypercoagulation and intrahepatic hypoxia. The present study provides evidence that serum ALT/LDH ratio aids in the identification of patients with ALI and intrahepatic hypoxia as a result of microcirculatory disturbance. The results facilitate the improved understanding of the pathogenesis of ALI, thereby offering a novel therapeutic strategy against ALI, which arises from sinusoidal hypercoagulation.

Lysosomal instability and cathepsin B release during acetaminophen hepatotoxicity

Acetaminophen (APAP) overdose is currently the most frequent cause of drug-induced liver failure in the United States. Recently, it was shown that lysosomal iron translocates to mitochondria where it contributes to the collapse of the mitochondrial membrane potential. Therefore, the purpose of this study was to investigate whether cathepsin B, a lysosomal protease, is involved in APAP-induced hepatotoxicity. Cathepsin B activity was measured in subcellular liver fractions of C57Bl/6 mice 3 hr after 300 mg/kg APAP treatment. There was a significant increase in cytoplasmic cathepsin activity, concurrent with a decrease in microsomal activity, indicative of lysosomal cathepsin B release. To investigate the effect of cathepsin B on hepatotoxicity, the cathepsin inhibitor AC-LVK-CHO was given 1 hr prior to 300 mg/kg APAP treatment along with vehicle control. There was no difference between groups in serum alanine aminotransferase (ALT) values, or by histological evaluation of necrosis, although cathepsin B activity was inhibited by 70-80% compared with controls. These findings were confirmed with a different inhibitor (z-FA-fmk) in vivo and in vitro. Hepatocytes were exposed to 5 mM acetaminophen. Lysotracker staining confirmed lysosomal instability and cathepsin B release, but there was no reduction in cell death after treatment with cathepsin B inhibitors. Finally, cathepsin B release was measured in clinical samples from patients with APAP-induced liver injury. Low levels of cathepsin B were released into plasma from overdose patients. APAP overdose causes lysosomal instability and release of cathepsin B into the cytosol but does not contribute to liver injury under these conditions.

Teduglutide, a glucagon-like peptide 2 analogue: a novel protective agent with anti-apoptotic and anti-oxidant properties in mice with lung injury

Teduglutide is a long-acting synthetic analogue of human glucagon-like peptide-2 (GLP-2). GLP-2 regulates cell proliferation and apoptosis as well as normal physiology in the gastrointestinal tract. In the present study, possible cytoprotective and reparative effects of teduglutide were analyzed on a mouse model with lung injury induced by tumor necrosis factor-alpha (TNF-α) and actinomycin D (Act D). BALB/c mice were divided into six groups: control mice (I), mice injected intraperitoneally with 15 μg/kg TNF-α (II), 800 μg/kg Act D (III), Act D 2 min prior to TNF-α administration with the same doses (IV), mice injected subcutaneously with 200 μg/kg teduglutide every 12h for 10 consecutive days (V), and mice given Act D 2 min prior to TNF-α administration on day 11 after receiving teduglutide for 10 days (VI). The TNF-α/Act D administration made the lung a sensitive organ to damage. Mice lung subjected to TNF-α/Act D were characterized by the disruption of alveolar wall, induced pulmonary endothelial/epithelial cell apoptosis and expression of active caspase-3. These mice exhibited an increase in lipid peroxidation, glutathione levels, and activities of myeloperoxidase, superoxide dismutase, catalase, glutathione peroxidase and xanthine oxidase, as well as reduced tissue factor and sodium-potassium/ATPase activities. Teduglutide pretreatment regressed the structural damage, cell apoptosis and oxidative stress by reducing lipid peroxidation in mice received TNF-α/Act D. GLP-2 receptors were present on the cell membrane of type II pneumocytes and interstitial cells. Thus, teduglutide can be suggested as a novel protective agent, which possesses anti-apoptotic and anti-oxidant properties, against lung injury.

Z-FA.FMK activates duodenal epithelial cell proliferation through oxidative stress, NF-kappaB and IL-1beta in D-GalN/TNF-alpha-administered mice

This study was designed to evaluate the effect of Z-FA.FMK (benzyloxycarbonyl-l-phenylalanyl-alanine-fluoromethylketone), a pharmacological inhibitor of cathepsin B, on the proliferation of duodenal mucosal epithelial cells and the cellular system that controls this mechanism in these cells in vivo. For this investigation, BALB/c male mice were divided into four groups. The first group received physiological saline, the second group was administered Z-FA.FMK, the third group received D-GalN (D-galactosamine) and TNF-alpha (tumour necrosis factor-alpha) and the fourth group was given both D-GalN/TNF-alpha and Z-FA.FMK. When D-GalN/TNF-alpha was administered alone, we observed an increase in IL-1beta-positive and active NF-kappaB-positive duodenal epithelial cells, a decrease in PCNA (proliferative cell nuclear antigen)-positive duodenal epithelial cells and an increase in degenerative changes in duodenum. On the other hand, Z-FA.FMK pretreatment inhibited all of these changes. Furthermore, lipid peroxidation, protein carbonyl and collagen levels were increased, glutathione level and superoxide dismutase activity were decreased, while there was no change in catalase activity by D-GalN/TNF-alpha injection. On the contrary, the Z-FA.FMK pretreatment before D-GalN/TNF-alpha blocked these effects. Based on these findings, we suggest that Z-FA.FMK might act as a proliferative mediator which is controlled by IL-1beta through NF-kappaB and oxidative stress in duodenal epithelial cells of D-GalN/TNF-alpha-administered mice.

Trovafloxacin enhances TNF-induced inflammatory stress and cell death signaling and reduces TNF clearance in a murine model of idiosyncratic hepatotoxicity

Therapy employing the fluoroquinolone antibiotic, trovafloxacin (TVX) was curtailed due to idiosyncratic hepatotoxicity. Previous studies in mice showed that a nonhepatotoxic inflammatory stress induced by tumor necrosis factor alpha (TNF) synergized with a nonhepatotoxic dose of TVX to cause liver injury. The purpose of this study was to explore mechanisms by which TVX interacts with TNF to cause liver injury. TVX pretreatment prolonged the peak of plasma TNF after its administration. This prolongation of TNF by TVX was critical to the development of hepatotoxicity. The prolongation of TNF concentration in plasma was primarily due to reduced clearance when compared with secondary biosynthesis. TNF is cleared from plasma by binding to soluble TNF receptors (TNFRs) which are eliminated by the kidney; however, the plasma concentrations of soluble TNFRs were not reduced, and biomarkers of renal dysfunction were not elevated in TVX/TNF-treated mice. Two injections of TNF mimicked the prolongation of the TNF peak by TVX and caused liver injury, but injury was less severe than after TVX/TNF coexposure. TVX enhanced the induction of proinflammatory cytokines by TNF. Additionally, TVX sensitized Hepa1c1c7 cells to TNF-induced killing in a concentration-dependent manner and increased both potency and efficacy of TNF to activate effector caspases that were critically involved in cell death from TVX/TNF coexposure. In summary, TVX reduced the clearance of TNF independent of either receptor shedding or kidney dysfunction. Additionally, TVX interacted with TNF to enhance inflammation and sensitize hepatocytes to TNF-induced cell death.

Tumor necrosis factor alpha is a proximal mediator of synergistic hepatotoxicity from trovafloxacin/lipopolysaccharide coexposure

The use of trovafloxacin (TVX), a fluoroquinolone antibiotic, was severely restricted because of an association of TVX therapy with idiosyncratic hepatotoxicity in patients. The mechanisms underlying idiosyncratic toxicity are unknown; however, one hypothesis is that an inflammatory stress can render an individual sensitive to the drug. Previously, we reported that treatment of mice with TVX and lipopolysaccharide (LPS) induced tumor necrosis factor (TNF) alpha-dependent liver injury, whereas TVX or LPS treatment alone was nontoxic. The goal of this study was to elucidate the role of TNFalpha in TVX/LPS-induced liver injury. TNF receptor (TNFR) 1 p55(-/-) and TNFR2 (p75(-/-)) mice were protected from hepatotoxicity caused by TVX/LPS coexposure, suggesting that TVX/LPS-induced liver injury requires both TNF receptors. TNFalpha inhibition using etanercept significantly reduced the TVX/LPS-induced increases in the plasma concentrations of several cytokines around the time of onset of liver injury. However, despite the reduction in chemokines, etanercept treatment did not affect the TVX/LPS-induced hepatic accumulation of neutrophils. In addition, etanercept treatment attenuated TVX/LPS induction of plasminogen activator inhibitor-1, and this was associated with a reduction in hepatic fibrin deposition. Mice treated with TVX and a nontoxic dose of TNFalpha also developed liver injury. In summary, TNFalpha acts through p55 and p75 receptors to precipitate an innocuous inflammatory cascade. TVX enhances this cascade, converting it into one that results in hepatocellular injury.

Effects of Z-FA.FMK on D-galactosamine/tumor necrosis factor-alpha-induced kidney injury and oxidative stress in mice : effects of Z-FA.FMK on TNF-alpha-mediated kidney injury

BACKGROUND

The aim of this investigation was to demonstrate that benzyloxicarbonyl-L-phenylalanyl-alanine-fluoromethylketone (Z-FA.FMK), which is a pharmacological inhibitor of cathepsin B, has protective role on the kidney injury that occurs together with liver injury. Methods BALB/c male mice used in this study were divided into four groups. The first group was given physiologic saline only, the second group was administered Z-FA.FMK alone, the third group received D: -galactosamine and tumor necrosis factor-alpha (D-GalN/TNF-alpha), and the fourth group was given both D-GalN/TNF-alpha and Z-FA.FMK. One hour after administration of 8 mg/kg Z-FA.FMK by intravenous injection, D-GalN (700 mg/kg) and TNF-alpha (15 microg/kg) were given by intraperitoneal injection. Results In the group given D-GalN/TNF-alpha, the following results were found: severe degenerative morphological changes in the kidney tissue, a significant increase in the number of activated caspase-3-positive tubular epithelial cell, an insignificant increase in the number of proliferating cell nuclear antigen (PCNA)-positive tubular epithelial cell, a decrease in the kidney glutathione (GSH) levels, catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities, an increase in the kidney lipid peroxidation (LPO) levels, lactate dehydrogenase (LDH) activity, serum aspartate aminotransferase (AST), and alanine aminotransferase (ALT) activities, uric acid and urea levels. In contrast, in the group given D-GalN/TNF-alpha and Z-FA.FMK, a significant decrease in the D-GalN/TNF-alpha-induced degenerative changes, a decrease in the number of activated caspase-3-positive tubular epithelial cell, a insignificant decrease in the number of PCNA-positive tubular epithelial cell, an increase in the kidney GSH levels, CAT, SOD and GPx activities, a decrease in the kidney LPO levels, LDH activity, serum AST and ALT activities, uric acid and urea levels were determined. Conclusion These results suggest that pretreatment with Z-FA.FMK markedly lessens the degree of impairment seen in D-GalN/TNF-alpha-induced kidney injury, which occurred together with liver injury in mice.