Insight on ALPPS - Associating Liver Partition and Portal Vein Ligation for Staged Hepatectomy - mechanisms: activation of mTOR pathway.

BACKGROUND: ALPPS procedure has been introduced to increase the volume of future liver remnant. The mechanisms underlying the accelerated regeneration observed with ALPPS are unknown. It was hypothesized that AMPK/mTOR is activated as an integrating pathway for metabolic signals leading to proliferation and cell growth. Our aim was to analyze increase in liver volume, proliferation parameters and expression of AMPK/mTOR pathway-related molecules in patients undergoing ALPPS. METHODS: A single center prospective study of patients undergoing ALPPS was performed from 2013 to 2015. Liver and serum samples, clinical laboratory results and CT-scan data were obtained. ELISA, Ki-67 immunostaining and qRT-PCR were performed in deportalized and remnant liver tissue in both stages of the procedure. RESULTS: 11 patients were enrolled. Remnant liver volume increased 112 ± 63% (p < 0.05) in 9.1 ± 1.6 days. Proliferation-related cytokines IL-6, TNF-α, HGF and EGF significantly increased, while higher Ki-67 immunostaining and cyclin D expression were observed in remnant livers after ALPPS. mTOR, S6K1, 4E-BP1, TSC1 and TSC2 expression were significantly increased in remnant livers at second stage, while AMPK and Akt increased only in deportalized liver samples. CONCLUSION: Rapid liver regeneration with ALPPS might be associated with hepatocyte proliferation induced by mTOR pathway activation.

Anti-Apoptotic Effects of 3,3',5-Triiodo-L-Thyronine in the Liver of Brain-Dead Rats.

BACKGROUND: Thyroid hormone treatment in brain-dead organ donors has been extensively studied and applied in the clinical setting. However, its clinical applicability remains controversial due to a varying degree of success and a lack of mechanistic understanding about the therapeutic effects of 3,3',5-Triiodo-L-thyronine (T3). T3 pre-conditioning leads to anti-apoptotic and pro-mitotic effects in liver tissue following ischemia/reperfusion injury. Therefore, we aimed to study the effects of T3 pre-conditioning in the liver of brain-dead rats. METHODS: Brain death (BD) was induced in mechanically ventilated rats by inflation of a Fogarty catheter in the epidural space. T3 (0.1 mg/kg) or vehicle was administered intraperitoneally 2 h prior to BD induction. After 4 h of BD, serum and liver tissue were collected. RT-qPCR, routine biochemistry, and immunohistochemistry were performed. RESULTS: Brain-dead animals treated with T3 had lower plasma levels of AST and ALT, reduced Bax gene expression, and less hepatic cleaved Caspase-3 activation compared to brain-dead animals treated with vehicle. Interestingly, no differences in the expression of inflammatory genes (IL-6, MCP-1, IL-1ß) or the presence of pro-mitotic markers (Cyclin-D and Ki-67) were found in brain-dead animals treated with T3 compared to vehicle-treated animals. CONCLUSION: T3 pre-conditioning leads to beneficial effects in the liver of brain-dead rats as seen by lower cellular injury and reduced apoptosis, and supports the suggested role of T3 hormone therapy in the management of brain-dead donors.

N-3 long-chain PUFA supplementation prevents high fat diet induced mouse liver steatosis and inflammation in relation to PPAR-α upregulation and NF-κB DNA binding abrogation.

SCOPE: Dietary n-3 long-chain PUFAs (n-3 LCPUFAs) supplementation was studied in an HFD-induced (HFD is high-fat diet) steatosis and inflammation in relation to peroxisome proliferator-activated receptor alpha (PPAR-α) and nuclear factor κB (NF-κB) signaling. METHODS AND RESULTS: Male C57BL/6J mice received (i) control diet (10% fat, 20% protein, 70% carbohydrate), (ii) control diet plus n-3 LCPUFAs (daily doses of 108 mg/kg body weight of eicosapentaenoic acid plus 92 mg/kg body weight of docosahexaenoic acid), (iii) HFD (60% fat, 20% protein, 20% carbohydrate), or (iv) HFD plus n-3 LCPUFAs for 12 wk. PPAR-α, tumor necrosis factor alpha (TNF-α), and IL-1ß mRNA expression, acyl-CoA oxidase 1 (ACOX1), and carnitine-acyl-CoA transferase 1 (CAT-I) protein contents, and NF-κB DNA binding activity were measured. HFD significantly decreased liver PPAR-α, ACOX1, and CAT-I levels with NF-κB activation, higher TNF-α and IL-1ß expression, and steatosis development. These changes were either reduced or normalized to control values in animals subjected to HFD plus n-3 LCPUFAs, with establishment of an inverse association between NF-κB activation and PPAR-α mRNA expression (r = -0.66, p < 0.0001). CONCLUSION: Data presented indicate that n-3 LCPUFAs supplementation prevents liver steatosis and inflammation induced by HFD, with underlying mechanisms involving enhanced PPAR-α signaling and diminished NF-κB activation.

Hormonal pretreatment preserves liver regenerative capacity and minimizes inflammation after partial hepatectomy.

INTRODUCTION: The treatment of brain dead donors with combined hormonal resuscitation protocols, including methylprednisolone (MP) and triiodothyronine (T3), among others, was developed to increase the viability and function of transplanted organs, primarily heart and lung. Even when it has regarded successful results in term of donors and organs recovery, its effects over specific parameters in organs like the liver are unknown. MATERIAL AND METHODS: Male Sprague-Dawley rats were pretreated with MP (0.34 mg/kg) and/or T3 (0.05 mg/kg) or their vehicles, and then subjected to partial hepatectomy of 70%. Three experimental groups and their respective controls were conformed: a. T3; b. NaOH; c. MP; d. vMP; e. MP+T3 and f. vMP+NaOH. The groups were evaluated at 0, 16, 24, 72 and 120 h post surgery. The effects of this protocol on regeneration, liver mass recovery, liver injury, oxidative stress and liver function were analyzed. RESULTS: MP+T3 pretreatment does not deleteriously affect liver regeneration after partial hepatectomy, as shown in the curve of total mass recovery, Ki67 staining and mitosis counting, and does not alter liver function. In addition, the treatment modestly decreases oxidative stress and liver injury, as evidenced by transaminases levels, histological analysis and oxidized proteins content. CONCLUSION: These preclinical results indicate that MP+T3 is harmless for liver tissue regeneration post hepatectomy and additionally exhibits anti-inflammatory and antioxidant effects; therefore, it would not be contraindicated for the treatment of multiorgan donors in brain death and particularly, if the occurrence of small for size syndrome is suspected.

Thyroid hormone-induced cytosol-to-nuclear translocation of rat liver Nrf2 is dependent on Kupffer cell functioning.

L-3,3',5-triiodothyronine (T(3)) administration upregulates nuclear factor-E2-related factor 2 (Nrf2) in rat liver, which is redox-sensitive transcription factor mediating cytoprotection. In this work, we studied the role of Kupffer cell respiratory burst activity, a process related to reactive oxygen species generation and liver homeostasis, in Nrf2 activation using the macrophage inactivator gadolinium chloride (GdCl(3); 10 mg/kg i.v. 72 h before T(3) [0.1 mg/kg i.p.]) or NADPH oxidase inhibitor apocynin (1.5 mmol/L added to the drinking water for 7 days before T(3)), and determinations were performed 2 h after T(3). T(3) increased nuclear/cytosolic Nrf2 content ratio and levels of heme oxygenase 1 (HO-1), catalytic subunit of glutamate cysteine ligase, and thioredoxin (Western blot) over control values, proteins whose gene transcription is induced by Nrf2. These changes were suppressed by GdCl(3) treatment prior to T(3), an agent-eliciting Kupffer-cell depletion, inhibition of colloidal carbon phagocytosis, and the associated respiratory burst activity, with enhancement in nuclear inhibitor of Nrf2 kelch-like ECH-associated protein 1 (Keap1)/Nrf2 content ratios suggesting Nrf2 degradation. Under these conditions, T(3)-induced tumor necrosis factor-α (TNF-α) response was eliminated by previous GdCl(3) administration. Similar to GdCl(3), apocynin given before T(3) significantly reduced liver Nrf2 activation and HO-1 expression, a NADPH oxidase inhibitor eliciting abolishment of colloidal carbon-induced respiratory burst activity without altering carbon phagocytosis. It is concluded that Kupffer cell functioning is essential for upregulation of liver Nrf2-signaling pathway by T(3). This contention is supported by suppression of the respiratory burst activity of Kupffer cells and the associated reactive oxygen species production by GdCl(3) or apocynin given prior to T(3), thus hindering Nrf2 activation.

Prevention of liver ischemia reperfusion injury by a combined thyroid hormone and fish oil protocol.

Several preconditioning strategies are used to prevent ischemia-reperfusion (IR) liver injury, a deleterious condition associated with tissue resection, transplantation or trauma. Although thyroid hormone (T3) administration exerts significant protection against liver IR injury in the rat, its clinical application is controversial due to possible adverse effects. Considering that prevention of liver IR injury has also been achieved by n-3 polyunsaturated fatty acid (n-3 PUFA) supplementation to rats, we studied the effect of n-3 PUFA dietary supplementation plus a lower dose of T3 against IR injury. Male Sprague-Dawley rats receiving fish oil (300 mg/kg) for 3 days followed by a single intraperitoneal dose of 0.05 mg T3/kg were subjected to 1 h of ischemia followed by 20 h of reperfusion. Parameters of liver injury (serum transaminases, histology) and oxidative stress (liver contents of GSH and oxidized proteins) were correlated with fatty acid composition, NF-κB activity, and tumor necrosis factor-α (TNF-α) and haptoglobin expression. IR significantly modified liver histology; enhanced serum transaminases, TNF-α response or liver oxidative stress; and decreased liver NF-κB activity and haptoglobin expression. Although IR injury was not prevented by either n-3 PUFA supplementation or T3 administration, substantial decrease in liver injury and oxidative stress was achieved by the combined protocol, which also led to increased liver n-3 PUFA content and decreased n-6/n-3 PUFA ratios, with recovery of NF-κB activity and TNF-α and haptoglobin expression. Prevention of liver IR injury achieved by a combined protocol of T3 and n-3 PUFA supplementation may represent a novel noninvasive preconditioning strategy with potential clinical application.

Thyroid hormone administration induces rat liver Nrf2 activation: suppression by N-acetylcysteine pretreatment.

BACKGROUND: Oxidative stress associated with 3,3',5-triiodo-l-thyronine (T(3))-induced calorigenesis upregulates the hepatic expression of mediators of cytoprotective mechanisms. The aim of this study was to evaluate the hypothesis that in vivo T(3) administration triggers a redox-mediated translocation of the cytoprotective nuclear transcription factor erythroid 2-related factor 2 (Nrf2) from the cytosol to the nucleus in rat liver. Such translocation of transcription factors is considered to be an activating step. MATERIALS AND METHODS: The effect of T(3) administration in the presence and absence of N-acetylcysteine (NAC) on cytosol-to-nuclear translocation of Nrf2 was evaluated, with inhibition of this process by NAC taken as evidence that the process was redox mediated. Male Sprague-Dawley rats weighing 180-200 g were given a single intraperitoneal dose of 0.1 mg T(3)/kg. Another group of rats were given the same dose of T(3) and were also pretreated with NAC (0.5 g/kg) at 0.5 hour before T(3) administration. Two other groups of rats received vehicle treatment and NAC, respectively. Following these treatments, rectal temperature of the animals, liver O(2) consumption, serum and hepatic levels of 8-isoprostanes, and liver protein levels of Nrf2, Akt, p38, and thioredoxin (Western blot) were determined at different times up to 48 hours. RESULTS: T(3) administration induced a significant increase in the hepatic nuclear levels of Nrf2 at 1 and 2 hours after treatment and a concomitant decrease in cytosolic Nrf2. It also increased hepatic thioredoxin, a protein whose gene transcription is induced by nuclear Nrf2. Levels of nuclear Nrf2 were at a plateau from 4 to 6 hours after T(3). Rectal temperature of the animals rose from 36.6°C to 37.5°C as did liver O(2) consumption. Serum and liver 8-isoprostanes levels increased (p < 0.05) from 38.4 ± 4.0 pg/mL (n = 4) to 69.2 ± 2.0 pg/mL (n = 3) and from 0.75 ± 0.09 ng/g liver (n = 3) to 1.53 ± 0.10 ng/g liver (n = 5), respectively. In the group of rats pretreated with NAC, the increase in cytosol-to-nuclear translocation of Nrf2 was only 28% that induced by T(3). In addition, T(3) induced liver Akt and p38 activation during the period of 1-4 hours after T(3) administration. p38 activation at 2 hours after T(3) administration was abolished in NAC-pretreated animals. CONCLUSIONS: In vivo T(3) administration leads to a rapid and transient cytosol-to-nuclear translocation of liver Nrf2. This appears to be promoted by a redox-dependent mechanism as it is blocked by NAC. It may also be contributed by concomitant p38 activation, which in turn promoted Nrf2 phosphorylation. Nrf2 cytosol-to-nuclear translocation may represent a novel cytoprotective mechanism of T(3) to limit free radical or electrophile toxicity, as this would likely entail promoting thioredoxin production.

Effect of sorafenib on murine liver regeneration.

UNLABELLED: Hepatocellular carcinoma (HCC) is a common cause of cancer-related death. Sorafenib prolongs survival of patients with advanced disease and is approved for the systemic treatment of unresectable HCC. It possesses antiangiogenic and antiproliferative properties by way of inhibition of the receptor tyrosine kinases vascular endothelial growth factor receptor 2 (VEGFR-2) and platelet-derived growth factor receptor-beta 1/2 (PDGFR-ß) and the kinase RAF. Sorafenib represents a candidate compound for adjuvant therapy in HCC patients. The aim of our study was to investigate whether sorafenib affects liver regeneration. C57BL6 mice received sorafenib orally at 30 mg/kg/day or its vehicle either for 14 days until the day before hepatectomy or starting the day after surgery or both. Animals were sacrificed 24, 72, and 120 hours after hepatectomy. Liver regeneration was calculated as a percent of initial liver weight. Bromodeoxyuridine (BrdU) incorporation and phospho-extracellular signal-regulated kinase (pERK1/2) were determined by immunohistochemistry on liver sections. VEGF-A, PDGF-BB, and hepatocyte growth factor (HGF) levels were measured in liver tissue homogenates. Histological analysis of scar tissue was performed. Treatment stopped 1 day before surgery had no impact on liver regeneration. Continuous sorafenib treatment and treatment started 1 day after surgery had statistically significant effects on liver regeneration at 120 hours compared to vehicle-treated control animals (72% ± 12 versus control 88% ± 15 and 70% ± 13 versus control 86% ± 5 at 120 hours, both P ≤ 0.02). BrdU incorporation showed decreased numbers of positive nuclei in both groups receiving sorafenib after surgery. Phospho-ERK levels were reduced in sorafenib-treated animals. An increase of VEGF-A levels was observed in mice receiving sorafenib. Wound-healing complications were observed in animals receiving sorafenib after surgery and confirmed on histological sections. CONCLUSION: This preclinical study shows that sorafenib did not impact on liver regeneration when ceased before surgery; however, administration after hepatectomy affected late liver regeneration.

Ablation of the tumor suppressor histidine triad nucleotide binding protein 1 is protective against hepatic ischemia/reperfusion injury.

UNLABELLED: The identification of cellular pathways capable of limiting ischemia/reperfusion (I/R) injury remains a frontier in medicine, and its clinical relevance is urgent. Histidine triad nucleotide binding protein 1 (HINT1) is a tumor suppressor that influences apoptosis. Because apoptotic pathways are a feature of I/R injury, we asked whether Hint1 influences hepatic I/R injury. Hint1(-/-) and C57BL/6 mice were subjected to 70% liver ischemia followed by reperfusion for 3 or 24 hours or to a sham operation. The serum aminotransferase levels, histological lesions, apoptosis, reactive oxygen species, and expression of B cell lymphoma 2-associated X protein (Bax), heme oxygenase 1 (HO-1), interleukin-6 (IL-6), IL-10, tumor necrosis factor-a, Src, nuclear factor kappa B (p65/RelA), and c-Jun were quantified. The responses to toll-like receptor ligands and nicotinamide adenine dinucleotide phosphate oxidase activity in Kupffer cells were compared in Hint1(-/-) mice and C57BL/6 mice. After I/R, the levels of serum aminotransferases, parenchymal necrosis, and hepatocellular apoptosis were significantly lower in Hint1(-/-) mice versus control mice. Furthermore, Bax expression decreased more than 2-fold in Hint1(-/-) mice, and the increases in reactive oxygen species and HO-1 expression that were evident in wild-type mice after I/R were absent in Hint1(-/-) mice. The phosphorylation of Src and the nuclear translocation of p65 were increased in Hint1(-/-) mice, whereas the nuclear expression of phosphorylated c-Jun was decreased. The levels of the protective cytokines IL-6 and IL-10 were increased in Hint1(-/-) mice. These effects increased survival after I/R in mice lacking Hint1. Hint1(-/-) Kupffer cells were less activated than control cells after stimulation with lipopolysaccharides. CONCLUSION: The Hint1 protein influences the course of I/R injury, and its ablation in Kupffer cells may limit the extent of the injury.

Targeting vessels to treat hepatocellular carcinoma.

The process of blood vessel proliferation, known as angiogenesis, is essential during embryonic development and organogenesis. In adult life, it participates in normal tissue repair, wound healing, and cyclical growth of the corpus luteum and the endometrium. Crucial as it is, angiogenesis can become pathological, and abnormal angiogenesis contributes to the pathogenesis of inflammatory and neoplasic diseases. The present review highlights the evidence for the role of angiogenesis in HCC (hepatocellular carcinoma) and discusses the increasing importance of inhibitors of angiogenesis in HCC therapy.

Involvement of Kupffer cell-dependent signaling in T3-induced hepatocyte proliferation in vivo.

Thyroid hormone-induced calorigenesis triggers liver oxidative stress with concomitant TNF-alpha production by Kupffer cells and up-regulation of gene expression. Considering that cyclin-dependent kinase-2 (CDK-2) performs essential functions for cellular proliferation, our aim was to test the hypothesis that l-3,3',5-triiodothyronine (T(3)) stimulates liver cell proliferation by upstream mechanisms involving CDK-2 expression dependent on Kupffer cell signaling. T(3) administration induced a calorigenic response at 60-70 h after treatment, with increased TNF-alpha generation and hepatic oxidative stress status, as shown by enhanced protein carbonyls and decreased glutathione content compared to controls. In this time interval, liver c-jun N-terminal kinase (JNK) phosphorylation, activator protein-1 (AP-1) DNA binding, and CDK-2 expression were enhanced, with concomitantly higher levels of the proliferation markers Ki-67 and proliferating cell nuclear antigen. These changes are abolished by administration of the Kupffer cell inactivator gadolinium chloride prior to T(3) treatment. We conclude that T(3) administration triggers liver CDK-2 expression and cellular proliferation through a cascade associated with Kupffer cell-dependent TNF-alpha generation, JNK phosphorylation, and AP-1 activation. Since CDK-2 promotes phase S progression within the cell cycle, this response may constitute a major mechanism involved in T(3)-induced liver preconditioning to ischemia/reperfusion injury.

Thyroid hormone preconditioning: protection against ischemia-reperfusion liver injury in the rat.

UNLABELLED: Recently, we reported that oxidative stress due to 3,3',5-triiodothyronine (T(3))-induced calorigenesis up-regulates the hepatic expression of mediators promoting cell protection. In this study, T(3) administration in rats (single dose of 0.1 mg/kg intraperitoneally) induced significant depletion of reduced liver glutathione (GSH), with higher protein oxidation, O(2) consumption, and Kupffer cell function (carbon phagocytosis and carbon-induced O(2) uptake). These changes occurred within a period of 36 hours of T(3) treatment in animals showing normal liver histology and lack of alteration in serum AST and ALT levels. Partial hepatic ischemia-reperfusion (IR) (1 h of ischemia via vascular clamping and 20 h reperfusion) led to 11-fold and 42-fold increases in serum AST and ALT levels, respectively, and significant changes in liver histology, with a 36% decrease in liver GSH content and a 133% increase in that of protein carbonyls. T(3) administration in a time window of 48 hours was substantially protective against hepatic IR injury, with a net 60% and 90% reduction in liver GSH depletion and protein oxidation induced by IR, respectively. Liver IR led to decreased DNA binding of nuclear factor-kappaB (NF-kappaB) (54%) and signal transducer and activator of transcription 3 (STAT3) (53%) (electromobility shift assay), with 50% diminution in the protein expression of haptoglobin (Western blot), changes that were normalized by T(3) preconditioning. CONCLUSION: T(3) administration involving transient oxidative stress in the liver exerts significant protection against IR injury, a novel preconditioning maneuver that is associated with NF-kappaB and STAT3 activation and acute-phase response.

Thyroid hormone-induced oxidative stress in rodents and humans: a comparative view and relation to redox regulation of gene expression.

Thyroid hormone (3,3',5-triiodothyronine, T(3)) exerts significant actions on energy metabolism, with mitochondria being the major target for its calorigenic effects. Acceleration of O(2) consumption by T(3) leads to an enhanced generation of reactive oxygen and nitrogen species in target tissues, with a higher consumption of cellular antioxidants and inactivation of antioxidant enzymes, thus inducing oxidative stress. This redox imbalance occurring in rodent liver and extrahepatic tissues with a calorigenic response, as well as in hyperthyroid patients, is further enhanced by an increased respiratory burst activity in Kupffer cells, which may activate redox-sensitive transcription factors such as NF-kappaB thus up-regulating gene expression. T(3) elicits an 80-fold increase in the serum levels of tumor necrosis factor-alpha (TNF-alpha), which is abolished by pretreatment with the antioxidants alpha-tocopherol and N-acetylcysteine, the Kupffer-cell inactivator GdCl(3), or an antisense oligonucleotide against TNF-alpha. In addition, T(3) treatment activates hepatic NF-kappaB, a response that is (i) inhibited by antioxidants and GdCl(3) and (ii) accompanied by induced mRNA expression of the NF-kappaB-responsive genes for TNF-alpha and interleukin (IL)-10. T(3) also increases the hepatic levels of mRNA for IL-1alpha and those of IL-1alpha in serum. Up-regulation of liver iNOS expression is also achieved by T(3), through a cascade initiated by TNF-alpha and involving IkappaB-alpha phosphorylation and NF-kappaB activation. In conclusion, T(3)-induced oxidative stress in the liver enhances the DNA-binding of NF-kappaB and the NF-kappaB-dependent expression of cytokines and iNOS by actions primarily exerted at the Kupffer cell level.

Early histological and functional effects of chronic copper exposure in rat liver.

Cu is an essential trace element capable of producing toxic effects in animals and man when ingested acutely or chronically in excess. Although chronic Cu exposure is increasingly recognized as a public health issue, its early effects remain largely unknown. We approached the significance of a moderate chronic Cu load in young rats to correlate early hepatic histopathological changes with functional alterations of liver cells. For this purpose, supplementation with 1,200 ppm of Cu in rat food for 16 weeks was chosen. In these conditions, Cu load elicited a significant decrease in growth curves. There were mild light microscopy alterations in Cu-treated rats, although increasing intracellular Cu storage was correlated with longer Cu exposure both by histological and biochemical measurements. Ultrastructural alterations included lysosomal inclusions as well as mitochondrial and nuclear changes. Liver perfusion studies revealed higher rates of basal O(2) consumption and colloidal carbon-induced O(2) uptake in Cu-treated rats, with enhanced carbon-induced O(2)/carbon uptake ratios and NF-kappaB DNA binding activity. These changes were time-dependent and returned to control values after 12 or 16 weeks. It is concluded that subchronic Cu loading in young rats induces early hepatic morphological changes, with enhancement in Küpffer cell-dependent respiratory burst activity and NF-kappaB DNA binding, cellular responses that may prevent or alleviate the hepatotoxicity of the metal.

Effects of acute lindane intoxication and thyroid hormone administration in relation to nuclear factor-kappaB activation, tumor necrosis factor-alpha expression, and Kupffer cell function in the rat.

Nuclear factor-kappaB (NF-kappaB) DNA binding, tumor necrosis factor-alpha (TNF-alpha) expression, and parameters related to liver oxidative stress and Kupffer cell function were assessed in control rats and in animals given 3,3',5-triiodothyronine (T3) (0.1 mg T3/kg) and/or lindane (50 mg/kg; 4 h after T3). Liver NF-kappaB DNA binding and serum TNF-alpha levels were enhanced by the combined T3-lindane administration after 16-22 h, effects that were lower than those elicited by the separate treatments and coincided with increased hepatic TNF-alpha mRNA levels. Thyroid calorigenesis occurred independently of lindane, whereas T3, lindane and T3-lindane groups showed liver glutathione (GSH) depletion, with higher protein carbonyl levels in lindane and T3-lindane groups. Carbon-induced O2 consumption/carbon uptake ratios were not altered by T3 or lindane compared to controls, whereas combined T3-lindane administration elicited a 92% diminution with enhancement in the sinusoidal efflux of lactate dehydrogenase (LDH). In conclusion, depression of T3- or lindane-induced liver NF-kappaB activation and TNF-alpha expression occurred after their combined treatment, effects that correlate with the impairment of the respiratory burst activity of Kupffer cells and exacerbation of liver injury.

Kupffer cell stimulation in the isolated perfused rat liver triggers nuclear factor-kappaB DNA binding activity.

Activation of transcription factor NF-kappaB (electrophoretic mobility shift assay) was investigated in the isolated perfused rat liver infused with 0.5 mg of colloidal carbon/ml for 5-20 min, in relation to carbon phagocytosis and carbon-induced O(2) consumption. Experiments were carried out in control rats and in animals treated with the Kupffer cell inactivator gadolinium chloride (GdCl(3)). Carbon uptake and carbon-induced O(2) consumption by perfused livers exhibited a linear increase as a function of the perfusion time, leading to constant O(2)/carbon uptake ratios, with low (0.04-0.15%) fractional sinusoidal lactate dehydrogenase release in the 5-20 min perfusion time studied. NF-kappaB DNA binding activity showed a maximal enhancement at 10 min of carbon perfusion, a response that was sustained at a lower extent at 15 and 20 min of carbon stimulation. After 10 min of carbon infusion, NF-kappaB activation, carbon-induced O(2) consumption, and carbon uptake were diminished by 84%, 94%, and 64% by GdCl(3) treatment (P < 0.05), respectively. It is concluded that the respiratory burst of carbon-stimulated Kupffer cells triggers NF-kappaB activation in the isolated perfused liver, a response that is elicited under optimal conditions of Kupffer cell function and organ viability.