Kupffer cells

Introduction: Hepatocyte-Kupffer cell (KC) co-cultures represent a promising approach for in vitro modeling of complex interactions between parenchymal and non-parenchymal cells in the liver, responsible for drug-induced liver injury (DILI). In this study we aimed to compare hepatocyte monocultures with hepatocyte-KC co-cultures regarding some basic liver functions associated with the chemical defense system. These pathways involve transporters and enzymes the function of which is highly sensitive towards hepatotoxic events. Methods: CYP2B1/2 induction and the biliary and sinusoidal elimination of bilirubin (B) and taurocholate (TC) were studied in rat hepatocyte sandwich cultures compared with rat hepatocyte-KC sandwich co-cultures of 1:0, 6:1, 2:1 and 1:1 cell combinations representing the physiologic and pathologic conditions of the liver. Results: KCs decreased phenobarbital inducibility of CYP2B1/2 in a cell ratio dependent manner and activation of KCs by lipopolisacharide (LPS) amplified this effect. Similarly, KCs decreased the transport of B and its glucuronides (BG) in both sinusoidal and canalicular directions resulting in its intracellular accumulation. In contrast, the uptake and the efflux of TC were greater in the cocultures than in the hepatocyte monocultures. Immuno-labelling of sodium-dependent taurocholate transporter (Ntcp) revealed increased expression of the transporter in the presence of KCs. Discussion: Here we presented that KCs have a direct impact on some hepatocyte functions suggesting that the co-culture model may be more suitable for drug related hepatotoxicity studies than hepatocyte monocultures.

Background Gram-negative sepsis and its sequelae frequently complicate invasive procedures in patients with obstructive jaundice. In response to endotoxin, Kupffer cells secrete tumour necrosis factor (TNF), a pivotal early mediator of sepsis. An investigation was carried out into the specific role of Kupffer cell TNF secretion following endotoxin challenge in obstructive jaundice. Methods Survival following intraperitoneal administration of endotoxin (2·0, 0·02 and 0·0002 mg per 100 g) was determined in rats following bile duct ligation (BDL) or sham operation. Plasma TNF concentration was quantified following endotoxin administration (0·0002 mg per 100 g) at 1, 2 and 6 h. Subsequently, the effect of Kupffer cell blockade by gadolinium chloride on survival and plasma TNF concentration was assessed. Results Jaundiced animals showed a significantly increased mortality rate following intraperitoneal injection of endotoxin 2·0 mg per 100 g (BDL 100 per cent versus sham 0 per cent) and ...

The literature evidencing the role of iron in promoting a range of neoplasms in humans and animals prompted us to search for a possible association between chemically induced hemosiderosis and hemangiosarcomas in the liver of mice in selected studies conducted by the National Toxicology Program (NTP). Its historical control database was examined for studies in which treatment-related liver hemangiosarcoma was noted; 130 consecutive NTP studies in B6C3FI mice from Technical Report (TR)-340 to TR-493 were evaluated. Three compounds (2-butoxyethanol, p-nitroaniline. and para-chloroaniline) were associated with a relatively high incidence of Kupffer cell pigmentation consisting of hemosiderin in both sexes; only the male mice developed a relatively low incidence of treatment-related hemangiosarcoma. With a fourth compound (o-nitroanisole), a relatively low incidence (16/50, high-dose males) of chemical-related hemosiderosis was noted, with no associated increase of hemangiosarcoma. Two chemicals (pentachlorophenol and tetrafluoroethylene) increased the incidence of liver hemangiosarcoma in male and female mice. with no increase in Kupffer cell pigmentation. The overall association between liver hemangiosarcoma and Kupffer cell pigmentation was highly significant (p < 0.001). The cause for hemosiderosis in all cases was the erythrocytic hemolytic effect of the compounds. The reason for the sex-increased susceptibility for development of hemangiosarcoma is unknown but may be due to a hormone-related. reduced antioxidative defensive capacity through modulation of the activities of antioxidative enzymes.

Although significant research data exist on the pathophysiology of nonalcoholic steatohepatitis (NASH), finding an efficient treatment regimen for it remains elusive. The present study used sparstolonin B (SsnB), a novel TLR4 antagonist derived from the Chinese herb Sparganium stoloniferum, as a possible drug to mitigate early inflammation in NASH. This study used an early steatohepatitic injury model in high-fat-fed mice with CYP2E1-mediated oxidative stress as a second hit. SsnB was administered for 1 wk along with bromodichloromethane (BDCM), an inducer of CYP2E1-mediated oxidative stress. Results showed that SsnB administration attenuated inflammatory morphology and decreased elevation of the liver enzyme alanine aminotransferase (ALT). Mice administered SsnB also showed decreased mRNA expression of proinflammatory cytokines TNF-␣, IFN-␥, IL-1␤, and IL-23, while protein levels of both TNF-␣ and IL-1␤ were significantly decreased. SsnB significantly decreased Kupffer cell activation as evidenced by reduction in CD68 and monocyte chemoattractant protein-1 (MCP1) mRNA and protein levels with concomitant inhibition of macrophage infiltration in the injured liver. Mechanistically, SsnB decreased TLR4 trafficking to the lipid rafts, a phenomenon described by the colocalization of TLR4 and lipid raft marker flotillin in tissues and immortalized Kupffer cells. Since we have shown previously that NADPH oxidase drives TLR4 trafficking in NASH, we studied the role of SsnB in modulating this pathway. SsnB prevented NADPH oxidase activation in vivo and in vitro as indicated by decreased peroxynitrite formation. In summary, the present study reports a novel use of the TLR4 antagonist SsnB in mitigating inflammation in NASH and in parallel shows a unique molecular mechanism of decreasing nitrative stress. SsnB; inflammation; NADPH oxidase; p47phox; peroxynitrite NONALCOHOLIC STEATOHEPATITIS (NASH), a hepatic manifestation of metabolic syndrome, arises from an underlying condition of obesity (22). After nearly three decades there remains a void of drugs approved for the treatment of NASH.

Although significant research data exist on the pathophysiology of nonalcoholic steatohepatitis (NASH), finding an efficient treatment regimen for it remains elusive. The present study used sparstolonin B (SsnB), a novel TLR4 antagonist derived from the Chinese herb Sparganium stoloniferum, as a possible drug to mitigate early inflammation in NASH. This study used an early steatohepatitic injury model in high-fat-fed mice with CYP2E1-mediated oxidative stress as a second hit. SsnB was administered for 1 wk along with bromodichloromethane (BDCM), an inducer of CYP2E1-mediated oxidative stress. Results showed that SsnB administration attenuated inflammatory morphology and decreased elevation of the liver enzyme alanine aminotransferase (ALT). Mice administered SsnB also showed decreased mRNA expression of proinflammatory cytokines TNF-α, IFN-γ, IL-1β, and IL-23, while protein levels of both TNF-α and IL-1β were significantly decreased. SsnB significantly decreased Kupffer cell activat...

The function of microRNAs (miRNAs) during alcoholic liver disease (ALD) has recently become of great interest in biological research. Studies have shown that ALD associated miRNAs play a crucial role in the regulation of liver‐inflammatory agents such as tumour necrosis factor‐alpha (TNF‐α), one of the key inflammatory agents responsible for liver fibrosis (liver scarring) and the critical contributor of alcoholic liver disease. Lipopolysaccharide (LPS), a component of the cell wall of gram‐negative bacteria, is responsible for TNF‐α release by Kupffer cells. miRNAs are the critical mediators of LPS signalling in Kupffer cells, hepatocytes and hepatic stellate cells. Certain miRNAs, in particular miR‐155 and miR‐21, show a positive correlation in up‐regulation of LPS signalling when they are exposed to ethanol. ALD is related to enhanced gut permeability that allows the levels of LPS to increase, leads to increased secretion of TNF‐α by the Kupffer cells and subsequently promotes al...

A hepatitis B surface antigen (HBsAg) chronic carrier chimpanzee experimentally superinfected with delta virus (DV) developed chronic DV infection. Over a period of 12 months, serologic and biochemical changes were correlated with morphologic abnormalities of the liver. Severe hepatic necrosis and inflammation accompanied the initial acute episode of hepatitis on Day 35 after inoculation, followed by complete resolution of these lesions over the next 3 months. A second episode of hepatitis occurred on Day 145, and severe necrosis and inflammation recurred along with the reappearance of delta antigen in the hepatocytes. Delta antigen persisted in the liver following the second episode of hepatitis and has remained positive throughout the observation period of 1 year. During the initial acute episode, the hepatocytes exhibited foamy cytoplasmic changes resembling microvesicular fat. However, ultrastructural studies of the same cells revealed only vacuolization of the cytoplasm without...

Liver regeneration is an important process that allows for recovery from hepatic injuries caused by viruses, toxins, ischemia, surgery, and transplantation. Previously, we identified > 70 immediate-early genes induced in regenerating liver after hepatectomy, 41 of which were novel. While it is expected that the proteins encoded by these genes may have important roles in regulating progression through the GI phase of the cell cycle during regeneration, we were surprised to note that many of these "early" genes are expressed for extended periods during the hepatic growth response. Here we define several patterns of expression of immediate-early, delayed-early, and liver-specific genes during the 9-d period after hepatectomy. One pattern of induction parallels the major growth period of the liver that ends at 60-72 h after hepatectomy. A second pattern has two peaks coincident with the first and second G1 phases of the two hepatic cell cycles. A third group, which includes liver-specific genes such as C/EBPa, shows maximal expression after the growth period. Although the peak in DNA synthesis in nonparenchymal cells occur 24 h later than in hepatocytes, most of the genes studied demonstrate similar induction in both cell types. This finding suggests that the GO/GI transition oc- curs simultaneously in all cells in the liver, but that the G1 phase of nonparenchymal cells may be relatively prolonged. Finally, we examined the expression of > 70 genes in clinical settings that could induce liver regeneration, including after perfusion in a donor liver, hepatic ischemia, and fulminant he- patic failure. We found that a small number of early and liver- specific genes were selectively activated in human livers under these conditions, and we thereby provide a potential means of measuring the caliber of the regenerative response in clinical situations. (

Liver regeneration is an important process that allows for recovery from hepatic injuries caused by viruses, toxins, ischemia, surgery, and transplantation. Previously, we identified > 70 immediate-early genes induced in regenerating liver after hepatectomy, 41 of which were novel. While it is expected that the proteins encoded by these genes may have important roles in regulating progression through the GI phase of the cell cycle during regeneration, we were surprised to note that many of these "early" genes are expressed for extended periods during the hepatic growth response. Here we define several patterns of expression of immediate-early, delayed-early, and liver-specific genes during the 9-d period after hepatectomy. One pattern of induction parallels the major growth period of the liver that ends at 60-72 h after hepatectomy. A second pattern has two peaks coincident with the first and second G1 phases of the two hepatic cell cycles. A third group, which includes liver-specific genes such as C/EBPa, shows maximal expression after the growth period. Although the peak in DNA synthesis in nonparenchymal cells occur 24 h later than in hepatocytes, most of the genes studied demonstrate similar induction in both cell types. This finding suggests that the GO/GI transition oc- curs simultaneously in all cells in the liver, but that the G1 phase of nonparenchymal cells may be relatively prolonged. Finally, we examined the expression of > 70 genes in clinical settings that could induce liver regeneration, including after perfusion in a donor liver, hepatic ischemia, and fulminant he- patic failure. We found that a small number of early and liver- specific genes were selectively activated in human livers under these conditions, and we thereby provide a potential means of measuring the caliber of the regenerative response in clinical situations. (

The aim of this study was to evaluate tumour vascularity and Kupffer cell imaging in hepatocellular carcinoma (HCC) using contrast-enhanced ultrasonography (CEUS) with Sonazoid (perfluorobutane) and to compare performance with dynamic CT. Methods: We studied 118 nodules in 88 patients with HCC. HCC was diagnosed as a hyperenhancement lesion in the arterial phase with washout in the portal phase on dynamic CT or by percutaneous biopsy. We observed tumour vascularity at the early vascular phase (10-30 s after contrast injection) and Kupffer imaging at the postvascular phase (after 10 min). Results: Detection of vascularity at the early vascular phase was 88% in nodules that were found to be hypervascular on dynamic CT and 28% in hypo-/isovascular nodules; the detection of local recurrence nodules was 92%. The detection of vascularity was significantly lower in nodules .9 cm deep than in those #9 cm deep, but was not affected by tumour size. The detection of tumours at the post-vascular phase on CEUS was 83% in nodules with low density in the portal phase on dynamic CT and 82% in nodules with isodensity. The rate did not depend on the severity of underlying liver disease; rates decreased in nodules deeper than 9 cm, those smaller than 2 cm in diameter and in iso-enhancing nodules at the early vascular phase of CEUS. Conclusion: CEUS with Sonazoid is a useful tool for assessing the vascularity of HCC and is equal to that of dynamic CT; however, the detectability of HCC vascularity is affected by location.

We studied the role of Kupffer cell functioning in T 3 liver preconditioning against ischemia-reperfusion (IR) injury using the macrophage inactivator gadolinium chloride (GdCl 3 ) previous to T 3 treatment. Male Sprague-Dawley rats given a single i.p. dose of 0.1 mg T 3 /kg were subjected to 1 h ischemia followed by 20 h reperfusion, in groups of animals pretreated with 10 mg GdCl 3 /kg i.v. 72 h before T 3 or with the respective vehicles. IR resulted in significant enhancement of serum aspartate aminotransferase (3.3-fold increase) and tumor necrosis factor-␣ (93% increase) levels, development of liver damage, and diminished nuclear factor-B DNA binding over control values. These changes, which were suppressed by the T 3 administration prior to IR, persisted in animals given GdCl 3 before T 3 treatment, under conditions of complete elimination of ED2(+) Kupffer cells achieved in a time window of 72 h. It is concluded that Kupffer cell functioning is essential for T 3 liver preconditioning, assessed in a warm IR injury model by hepatic macrophage inactivation.

This study tested the hypothesis that acute iron overload (500 mg/kg) alters Kupffer cell functioning by promoting free radical reactions associated with the respiratory burst of liver macrophages, assessed in the isolated perfused rat liver under conditions of Kupffer cell stimulation by carbon infusion and inactivation by gadolinium chloride pretreatment. Total serum and hepatic iron levels were markedly enhanced compared with control values 2 to 24 hours after iron treatment. Total liver O 2 uptake progressively increased by iron overload reaching a maximum at 6 hours after treatment, an effect that was completely blocked by GdCl 3 . Concomitantly, carbon-induced GdCl 3 -sensitive liver O 2 uptake was either enhanced by 119% at 2 hours after iron overload, diminished compared with control values at 4 hours, or abolished at 6 hours. Iron-overloaded rats showed a marked increase in liver sinusoidal lactate dehydrogenase efflux at 4 and 6 hours after treatment, an effect that is exacerbated by carbon infusion and reduced (69%-89%) by GdCl 3 pretreatment. Both basal and carboninduced lactate dehydrogenase effluxes returned to control values at 24 hours after iron overload concomitantly with depression of the basal O 2 uptake, without development of iron-induced GdCl 3 -sensitive respiration or Kupffer cell activation by carbon infusion. It is concluded that iron overload induces a derangement in the Kupffer cell functional status represented by early increases in macrophagedependent respiratory activity, which may contribute to the concomitant liver injury that developed and to the impairment of both hepatic respiration and the macrophage response to particle stimulation observed at later times after treatment. (HEPATOLOGY 1998;27:1311-1316.) Iron overload can produce severe health effects when the capacity of the body for storage is exceeded. 1 Under these Abbreviations: TBARS, thiobarbituric acid reactants; LDH, lactate dehydrogenase.

The effect of gadolinium chloride (GdCl3) on the content of rat liver mitochondrial cytochromes was investigated in relation to the basal rate of O2 uptake and Kupffer cell functioning, assessed in liver perfusion studies. (1) A single dose of GdCl3 (10 mg/kg) produced a significant diminution in Kupffer cell functioning, evidenced by the decreases in colloidal carbon uptake and in carbon‐induced O2 uptake observed at 6–24 h after treatment, without changes in the sinusoidal lactate dehydrogenase efflux as index of tissue viability; at 48 h after GdCl3 administration, carbon phagocytosis was recovered to control values, whereas carbon‐induced O2 uptake remained lower than control values. (2) GdCl3 also caused a 34% decrease in the basal rate of O2 consumption of the liver at 24 h after treatment, which returned towards control values at 48 h. (3) The content of mitochondrial cytochromes c1 and c at 24 h after GdCl3 treatment was significantly reduced by 40 and 32%, respectively, whi...

The Innovation & Quality Consortium (IQ) Translational and ADME Sciences Leadership Group (TALG) working group for the ADME of therapeutic proteins evaluates the current practices, recent advances, and challenges in characterizing the PK and biodistribution of therapeutic proteins during drug development, and proposes recommendations to address these issues. Incorporating the in vitro, in vivo and in silico approaches discussed herein may provide a pragmatic framework to increase early understanding of PK/PD relationships, and aid translational modelling for first-in-human dose predictions.

Kupffer cells (KC) and lipopolysaccharide (LPS) interaction is the initial event leading to hepatic inflammation and fibrosis in many types of liver injury. We studied chemokine secretion by KC activated with LPS and the possible effect of the somatostatin analogue octreotide, in the regulation of this process. 2 KC isolated from Sprague-Dawley rats were cultured in the presence of LPS added alone or with different concentrations of octreotide for 24 and 48 h, and chemokine production was assessed in culture supernatants by ELISA. CC chemokine mRNA expression was assessed by semiquantitative RT-PCR. 3 Vehicle-stimulated KC produced a basal amount of CC and CXC chemokines. LPS-stimulated KC secreted significantly increased amounts of IL-8 (GRO/CINC-1) (Po0.001), MIP-2 (Po0.001), MCP-1 (Po0.001), and RANTES (Po0.01). 4 Octreotide inhibited LPS-induced secretion of the CC chemokines MCP-1 (Po0.05) and RANTES (Po0.05), but not the CXC chemokines IL-8 (GRO/CINC-1) and MIP-2, in a concentration-dependent manner. Downregulation of basal and LPS-induced mRNA expression of the CC chemokines was also observed in the presence of octreotide. 5 Pretreatment with phosphatidylinositol 3 (PI3)-kinase inhibitors reduced chemokine production by LPS-treated KC in both the mRNA and protein level. Furthermore, it prevented the octreotide inhibitory effect on LPS-induced chemokine secretion, indicating a possible involvement of the PI3kinase pathway. 6 In conclusion, these data demonstrate that chemokine secretion by KC can be differentially regulated by octreotide, and suggest that this somatostatin analogue may have immunoregulatory effects on resident liver macrophages.

Hepatic injury can lead to systemic and pulmonary inflammation through activation of NF-κB-dependent pathways and production of various proinflammatory cytokines. The exact mechanism remains unknown, although prior research suggests interleukin-1β (IL-1β) plays an integral role. Cultured murine alveolar macrophages were used to identify an optimized IL-1β-specific short interfering RNA (siRNA) sequence, which then was encapsulated in liposomes and administered intraperitoneally to transgenic HLL mice (5′-HIV-LTR-Luciferase). A 35% hepatic mass cryoablation in HLL and IL-1 receptor 1 knockout mice (IL1R1KO) was performed as a model for liver-induced pulmonary inflammation. IL-1β siRNA pretreatment effectively and significantly reduced circulating IL-1β levels at 4 h post-hepatic injury. IL-6 also was suppressed in mice with impaired IL-1 signaling pathways. NF-κB activation in the noninjured liver of HLL reporter mice pretreated with IL-1β siRNA was found to be reduced compared with ...

Heterogeneity and functional specialization among skin-resident macrophages are incompletely understood. In this study, we describe a novel subset of murine dermal perivascular macrophages that extend protrusions across the endothelial junctions in steady-state and capture blood-borne macromolecules. Unlike other skin-resident macrophages that are reconstituted by bone marrow-derived progenitors after a genotoxic insult, these cells are replenished by an extramedullary radio-resistant and UV-sensitive Bmi1 + progenitor. Furthermore, they possess a distinctive anti-inflammatory transcriptional profile, which cannot be polarized under inflammatory conditions, and are involved in repair and remodeling functions for which other skin-resident macrophages appear dispensable. Based on all their properties, we define these macrophages as Skin Transendothelial Radio-resistant Anti-inflammatory Macrophages (STREAM) and postulate that their preservation is important for skin homeostasis.

Review on the biological consequences of IL-18 injections on cellular, humoral, and neutrophil-mediated immunity against bacterial infections, even in the immunocompromised hosts. IL-18 has a potential to up-regulate the Th1 and Th2 immune responses. It is known that IL-18, in synergy with IL-12, augments the Th1 response to bacterial infections, but it also augments the Th2 response to allergic disorders in the absence of IL-12. Although the Th1 and Th2 immune responses cross-regulate each other, our recent murine studies have demonstrated that multiple, alternate-day IL-18 injections (but not a single injection) could augment not only the Th1 immune response but also the Th2 immune response, including IgM production against bacterial infection in mice. In addition, critically ill patients who suffer from severe surgical stresses, e.g., trauma injury, burn injury, and major surgery, are known to be highly susceptible to bacterial infections/sepsis, and their outcomes become extreme...

Although C-reactive protein (CRP) is a representative acute-phase protein produced by hepatocytes, the role of CRP in liver innate immunity remains unclear. Using C57BL/6 mice, the present study investigated how CRP affects the functions of liver macrophages, Kupffer cells, and natural killer / natural killer T (NK/NKT) cells under various conditions, including Escherichia coli infection, septic shock, and multiorgan dysfunction induced by interleukin (IL)-12/lipopolysaccharide (LPS) (generalized Shwartzman reaction [GSR]), and LPS-induced lethal hepatitis in Propionibacterium acnes-primed mice. When mice were challenged with a lethal dose of E. coli, synthetic CRP peptide decreased the mortality without decreasing serum tumor necrosis factor (TNF), presumably by enhancing the phagocytic activity of Kupffer cells. Synthetic CRP greatly decreased the production of TNF and reactive oxygen species from Kupffer cells and thereby rescued mice after lethal LPS challenge. CRP also decreased the mortality from GSR and lethal hepatitis by inhibiting TNF production from Kupffer cells, especially phagocytosing Kupffer cells. However, interferon-gamma production from NK/NKT cells was generally not so affected. CRP reportedly binds to Fc␥RI and Fc␥RII, and the injection of anti-Fc␥RII/III Ab into mice abrogated TNF production from, but increased the phagocytic activity of, Kupffer cells. Furthermore, CRP pretreatment restored the decreased phagocytic activity of Kupffer cells in burn-injured mice and decreased TNF production by Kupffer cells and thereby inhibited mortality after sublethal E. coli infection. If CRP was injected into mice at 1 hour after lethal E. coli challenge, it slightly but significantly increased the survival rate. Conclusion: CRP thus enhances the phagocytosis of Kupffer cells but decreases their TNF production in a complex manner in which the pathway by way of Fc␥RII may be involved. (HEPATOLOGY 2009;49: 2044-2054.) B acterial infection evokes an inflammatory reaction in the host, and exaggerated proinflammatory cytokine reactions cause multiorgan dysfunction syndrome (MODS) and subsequent mortality. However, proinflammatory cytokines such as tumor necrosis factor (TNF), interleukin (IL)-12, and interferon-gamma (IFN-␥), produced by macrophages/Kupffer cells or natural killer/natural killer T (NK/NKT) cells, activate phagocytic activity by macrophages/Kupffer cells and granulocytes to eliminate the bacteria. 1,2 Phagocytosis of invading

Although ursodeoxycholic acid (UDCA) has long been used for patients with chronic cholestatic liver diseases, particularly primary biliary cirrhosis, it may modulate the host immune response. This study investigated the effect of UDCA feeding on experimental hepatitis, endotoxin shock, and bacterial infection in mice. C57BL/6 mice were fed a diet supplemented with or without 0.3% (wt/vol) UDCA for 4 wk. UDCA improved hepatocyte injury and survival in concanavalin-A (Con-A)-induced hepatitis by suppressing IFN-γ production by liver mononuclear cells (MNC), especially NK and NKT cells. UDCA also increased survival after lipopolysaccharide (LPS)-challenge; however, it increased mortality of mice following Escherichia coli infection due to the worsening of infection. UDCA-fed mice showed suppressed serum IL-18 levels and production of IL-18 from liver Kupffer cells, which together with IL-12 potently induce IFN-γ production. However, unlike normal mice, exogenous IL-18 pretreatment did ...

Background: Evidence in the literature suggests that down-regulation of nitric oxide (NO) is associated with the pathophysiological conditions during visceral leishmaniasis (VL). Here we have investigated the mechanism that leads to the down regulation of systemic NO in the infected condition. Moreover, we have determined whether down regulation of NO is associated with increased generation of reactive oxygen species (ROS) during this disease. Therapeutic strategy targeting signaling molecules of these events was evaluated. Methods: Plasma protein-nitrotyrosine was examined by ELISA kit. Generation of superoxides and peroxynitrites was investigated by flow cytometry. NO bioavailability in endothelial cells was evaluated using DAF-2DA fluorescence. Ceramide contents were evaluated using FACS analysis, HPTLC and HPLC. Results: L. donovani infected reticulo-endothelial cells regulated the activity of eNOS and NAD(P)H oxidase in the endothelial cells through the generation of intercellular messenger, ceramide. Activation of SMases played an important role in the generation of ceramide in animals during chronic infection. These events led to generation of ROS within endothelial cells. Modulation of redox status of plasma and accumulation of ROS in endothelial cells were critically involved in the regulation of NO bioavailability in plasma of the infected animal. Endothelial dysfunction and decline of NO were resulted from an increased production of superoxide where upregulation of eNOS expression appeared as an ineffective compensatory event. Inhibition of ceramide generation increased NO bioavailability, prevented endothelial dysfunction and concomitant oxidative stress. Conclusion and general significance: Decreased NO bioavailability and endothelial dysfunction were the downstream of ceramide signaling cascade. ROS accumulation promoted peroxynitrite generation and reduced NO bioavailability. Inhibition of ceramide generation may be a potential therapeutic option in preventing the co-morbidity associated with VL.

Background: Evidence in the literature suggests that down-regulation of nitric oxide (NO) is associated with the pathophysiological conditions during visceral leishmaniasis (VL). Here we have investigated the mechanism that leads to the down regulation of systemic NO in the infected condition. Moreover, we have determined whether down regulation of NO is associated with increased generation of reactive oxygen species (ROS) during this disease. Therapeutic strategy targeting signaling molecules of these events was evaluated. Methods: Plasma protein-nitrotyrosine was examined by ELISA kit. Generation of superoxides and peroxynitrites was investigated by flow cytometry. NO bioavailability in endothelial cells was evaluated using DAF-2DA fluorescence. Ceramide contents were evaluated using FACS analysis, HPTLC and HPLC. Results: L. donovani infected reticulo-endothelial cells regulated the activity of eNOS and NAD(P)H oxidase in the endothelial cells through the generation of intercellular messenger, ceramide. Activation of SMases played an important role in the generation of ceramide in animals during chronic infection. These events led to generation of ROS within endothelial cells. Modulation of redox status of plasma and accumulation of ROS in endothelial cells were critically involved in the regulation of NO bioavailability in plasma of the infected animal. Endothelial dysfunction and decline of NO were resulted from an increased production of superoxide where upregulation of eNOS expression appeared as an ineffective compensatory event. Inhibition of ceramide generation increased NO bioavailability, prevented endothelial dysfunction and concomitant oxidative stress. Conclusion and general significance: Decreased NO bioavailability and endothelial dysfunction were the downstream of ceramide signaling cascade. ROS accumulation promoted peroxynitrite generation and reduced NO bioavailability. Inhibition of ceramide generation may be a potential therapeutic option in preventing the co-morbidity associated with VL.

Background and Aims: HEV infection is the most common cause of liver inflammation, but the pathogenic mechanisms remain largely unclear. We aim to explore whether HEV infection activates inflammasomes, crosstalk with antiviral interferon response, and the potential of therapeutic targeting. We measured IL-1β secretion, the hallmark of inflammasome activation, in serum of HEV-infected patients and rabbits, and in cultured macrophage cell lines and primary monocyte-derived macrophages. We found that genotypes 3 and 4 HEV infection in rabbits elevated IL-1β production. A profound increase of IL-1β secretion was further observed in HEVinfected patients (1,733 ± 1,234 pg/mL; n = 70) compared to healthy persons (731 ± 701 pg/mL; n = 70). Given that macrophages are the drivers of inflammatory response, we found that inoculation with infectious HEV particles robustly triggered NOD-like receptor family pyrin domain-containing 3 (NLRP3)

The low-affinity receptor for IgE (FcERH/ CD23) is a cell surface glycoprotein that plays a role in both cellular immunity and allergic inflammation. Its extracellular IgE-binding domain bears homology to C-type animal lectins, and the protein is, therefore, classified as a member of this superfamily. We predict that this lectin-like domain is sepa- rated from the cell membrane by an extensive region of a-helical coiled-coil structure, based upon sequence compari- sons with tropomyosin, the archetypal a-helical coiled-coil structure, and detection of characteristic heptad repeats. Anal- ysis of other receptor protein sequences identified a similar structural motif in other membrane-bound members of the C-type lectin superfamily, including the asialoglycoprotein receptor, the Kupffer cell receptor, and the B-cell differentiation antigen Lyb-2 (CD72). It appears that within the C-type lectin superfamily, there is a subfamily of structurally related membrane-bound receptor proteins that contain a-helical coiled-coil stalks of various lengths. The low-affinity receptor for IgE (FcERII/CD23) is a mem- brane-bound glycoprotein expressed on a number of different cell types including lymphocytes, eosinophils, platelets, and macrophages. Its interaction with IgE is responsible for the protective functions of cellular cytotoxicity and phagocytic clearance of antigen, but it is also associated with delayed allergic reactions. A soluble fragment of FceRII acts as a growth factor for B cells and up-regulates IgE synthesis (1, 2). The sequences of the human (3-6) and murine (7, 8) receptor reveal that FceRII is a member of the C-type animal lectin family (9), with a C-terminal domain that is homologous to those of other members of this family such as the asialogly- coprotein receptor (AsgpR) and other hepatic lectins. This domain is extracellular, and the protein has a cytoplasmic N terminus and is anchored by a single transmembrane region, in common with other membrane-bound hepatic lectins. Although FcERII is thus classified as a lectin, IgE binding to the lectin-like domain does not involve the recognition of carbohydrate . The region between the lectin-like domain and the mem- brane is the subject of this study. Sequence analysis of this region provides evidence of an extensive a-helical coiled-coil structure in FceRII, and examination of other receptor pro- tein sequences reveals similar coiled-coil structures in other membrane-bound members of the C-type lectin superfamily. We thus identify a subfamily of membrane proteins within the C-type lectin superfamily with the same overall architecture comprising extracellular lectin "heads" separated from the membrane by a-helical coiled-coil "stalks" of various lengths.

BackgroundIt remains controversial whether and which fatty acids are different between prostate cancer (PCa) and benign prostatic tissues (BPT) in association with occurrence, progression and racial disparity between African American (AA) and Caucasian American (CA) populations.MethodsTotal fatty acids (TFA) and free fatty acid (FFA) were determined on fresh frozen prostatic tissues including 26 PCa and 21 BPT from AA and CA patients by Gas chromatography with flame ionization detection (GC-FID) and Electrospray Ionization Mass Spectrometry (ESI-MS), respectively.ResultsIn all studied population, TFA in 8 out of 16 individual species, in total and in groups of saturated total fatty acid (STFA), mono-unsaturated total fatty acid (MUTFA), poly-unsaturated total fatty acid (PUTFA) and n-6 TFA were significantly higher in PCa than in BPT; FFA in 4 out of 10 individual species, in total and in groups of MUFFA, PUFFA, n-6 FFA and n-3 FFA were significantly higher in PCa than in BPT. The c...

Background Adenosine triphosphate (ATP) is secreted from hepatocytes under physiological conditions and plays an important role in liver biology through the activation of P2 receptors. Conversely, higher extracellular ATP concentrations, as observed during necrosis, trigger inflammatory responses that contribute to the progression of liver injury. Impaired calcium (Ca2+) homeostasis is a hallmark of acetaminophen (APAP)-induced hepatotoxicity, and since ATP induces mobilization of the intracellular Ca2+ stocks, we evaluated if the release of ATP during APAP-induced necrosis could directly contribute to hepatocyte death. Results APAP overdose resulted in liver necrosis, massive neutrophil infiltration and large non-perfused areas, as well as remote lung inflammation. In the liver, these effects were significantly abrogated after ATP metabolism by apyrase or P2X receptors blockage, but none of the treatments prevented remote lung inflammation, suggesting a confined local contribution ...

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Background and Objective: Liver fibrosis is the result of an excessive accumulation of extracellular matrix that develops when inflammation and chronic injury form scar tissue in the liver. Toll-like receptor 9 (TLR9) plays a central role in the innate immune response by recognition of pathogen-associated molecular patterns (PAMPs) and endogenous damage-associated molecular patterns (DAMPs). This study aimed to show the therapeutic effects of TLR9 antagonist oligonucleotide (ODN) 2088 on liver fibrogenesis. Materials and Methods: Mice were injected intraperitoneally with carbon tetrachloride (CCl 4 ) or corn oil twice weekly for up to 8 weeks. Mice were also injected with CpG ODN 2088 (50 µg/20 g) daily for the last 4 weeks. At sacrifice, the serum level of liver enzyme activity was measured. Expression of pro-inflammatory and pro-fibrotic biomarkers was analyzed in liver tissue. Results: TLR9 antagonist, CpG ODN 2088, remarkably decreased the haptic inflammation and fibrosis during CCl 4 administration. Treatment with CpG ODN 2088 resulted in reduced serum Alanine Aminotransferase (ALT) and Aspartate Aminotransferase (AST). That was paralleled with inhibition in the production of intrahepatic inflammatory and fibrotic factors including collagen, "-Smooth Muscle Actin (SMA), Transforming Growth Factor-beta (TGF-$), interleukin-6 (IL-6) and Tumor Necrosis Factor-alpha (TNF-"). Proliferation (Ki-67) and apoptosis (caspase-3) markers were highly suppressed after CpG ODN 2088 administration. Conclusion: Our results indicate that TLR9 antagonist, ODN 2088, showed protective effects against hepatics inflammation and fibrosis in the CCl 4 -induced fibrosis model. These observations suggest that ODN 2088 can be a potential therapeutic target for liver fibrosis treatment.

Adverse immunological reactions to adenoviral vectors have significantly impacted the utility of this virus for treating genetic and environmentally induced diseases. In this study, we evaluate the effect of adenoviral vectors on an animal model of sepsis. Systemic delivery of first-generation adenoviral vectors to septic mice (cecal ligation and puncture) resulted in a shortened survival time. This effect was not observed with second-generation or inactivated first-generation vectors. The accelerated death was accompanied by a number of important changes in the disease. These changes included increased liver cell apoptosis (including Kupffer cells) and a marked increase in liver bacterial load. In the lung, the combination induced an increase in bacterial load, as well as greater lung injury. In the serum, the combination was associated with decreased TNF-α levels and an increase in bacterial load. Finally, a profound degree of lymphocyte apoptosis was observed in these animals. Th...

In the nuclear industry, wound contamination with americium is expected to increase with decommissioning and waste management. Treatment of workers with diethylenetriaminepentaacetic acid (DTPA) requires optimization to reduce internal contamination and radiation exposure. This work aimed at evaluating and comparing different DTPA protocol efficacies after wound contamination of rats with americium. Wound contamination was simulated in rats by depositing americium nitrate in an incision in the hind limb. Different routes, times, and frequencies of DTPA administration were evaluated. Individual daily urinary americium excretion and tissue retention were analyzed using the statistical tool STATBIODIS. Urinary profiles, urinary enhancement factors, and inhibition percentages of tissue retention were calculated. A single DTPA administration the day of contamination induced a rapid increase in americium urinary excretion that decreased exponentially over 7 d, indicating that the first DT...

We hypothesized that superoxide from Kupffer cells (KC) contributes to hepatocarcinogenesis. p47phox À/À mice, deficient in phagocyte NADPH oxidase and superoxide generation, received a single dose of the hepatocarcinogen diethylnitrosamine (DEN). The following hepatic effects were observed at time points between 30 min and 35 days. Liver damage after DEN was manifested by loss of body and liver mass and of liver DNA and by an increase in apoptosis, necrosis and signs of inflammation. These effects were massive in wild-type (wt) male mice, but only very mild in p47phox À/À mice. Regenerative DNA synthesis subsequent to liver damage was high in wt male mice, but weak in p47phox À/À mice. In females the apparent protection by p47phox À/À was less pronounced than in males. Therefore, further experiments were performed with males. In KC isolated from wt mice superoxide production was enhanced by DEN pretreatment in vivo. Also, in vitro addition of DEN to KC cultures induced superoxide release, similarly to lipopolysaccharide, a standard KC activator. Thus, DEN directly activates wt KC to produce superoxide. KC from p47phox À/À mice did not release superoxide. TNFa production by isolated KC was transiently depressed 0.5 h after DEN treatment in vivo, but recovered rapidly. In blood serum TNFa levels of wt mice were elevated for the initial 6 h. TNFa in KC cultures and in serum of p47phox À/À mice was reduced. DEN in vivo induced DNA damage ('comets') in hepatocytes. This damage was extensive in wt mice but much less in p47phox À/À mice. These studies suggest two conclusions: (i) superoxide generation by phagocytes during liver damage and inflammation aggravates genotoxic and cytotoxic effects in hepatocytes and may thus contribute to tumor initiation and promotion; (ii) DEN has a direct stimulatory effect on KC to release superoxide and TNFa.

Unlike naive T cells, effector T cells can be activated by either T cell receptor signal or costimulatory signal alone and therefore the absence of costimulatory molecules on tissue cells cannot explain the tolerance mechanism at the effector phase. Here we report that PD-L1, the ligand for the immunoinhibitory receptor PD-1, was expressed on vascular endothelium in peripheral tissues. Liver nonparenchymal cells including sinusoidal endothelial cells and Kupffer cells constitutively expressed PD-L1 and inhibited proliferation and cell division of activated T cells expressing PD-1. The absence of PD-1 induced proliferation of effector T cells in the adenovirus-infected liver and resulted in rapid clearance of the virus. These results indicate that PD-1 plays an important role in T cell tolerance at the effector phase and the blockade of the PD-1 pathway can augment antiviral immunity.

OBJECTIVE An increase in the rate of hepatic glucose production is the major determinant of fasting hyperglycemia in type 2 diabetes. A better understanding of the signaling pathways and molecules that regulate hepatic glucose metabolism is therefore of great clinical importance. Recent studies suggest that an increase in vagal outflow to the liver leads to decreased hepatic glucose production and reduced blood glucose levels. Since acetylcholine (ACh) is the major neurotransmitter of the vagus nerve and exerts its parasympathetic actions via activation of muscarinic ACh receptors (mAChRs), we examined the potential metabolic relevance of hepatocyte mAChRs. RESEARCH DESIGN AND METHODS We initially demonstrated that the M3 mAChR is the only mAChR subtype expressed by mouse liver/hepatocytes. To assess the physiological role of this receptor subtype in regulating hepatic glucose fluxes and glucose homeostasis in vivo, we used gene targeting and transgenic techniques to generate mutant...

Alterations of glucose metabolism and the oxidation of glutamine and palmitate were studied, by using specifically labelled substrates, in freshly isolated Kupffer cells and hepatic endothelial cells after infusion in vivo of human recombinant tumour necrosis factor-a (TNF; 7.5 x 105 IU/30 min per kg body wt., intravenously). Cells were incubated in a medium containing 5 mM-glucose, 0.4 mM-palmitate, I mM-lactate and 0.5 mM-glutamine. Administration of TNF in vivo increased glucose use in Kupffer cells by 70 %. Glucose oxidation in the tricarboxylic acid cycle and flux in the Embden-Meyerhof (EM) pathway were elevated by 40 and 800% respectively. Treatment in vitro with 1 /tM-phorbol 12-myristate 13-acetate (PMA) resulted in a similar percentage increase in glucose use by Kupffer cells prepared from either saline-or TNF-treated rats. However, PMA increased the activity of the hexose monophosphate shunt (HMS) by 3-and 10-fold in cells isolated from salineor TNF-infused animals respectively. A phagocyte stimulus in vitro, opsonized zymosan, increased glucose use by 30 % and doubled the flux through the HMS in Kupffer cells from saline-infused animals. The activity of the HMS in response to zymosan was increased by 400 % after TNF treatment. In endothelial cells, basal glucose utilization was not altered by TNF treatment. PMA increased HMS activity in endothelial cells to a similar degree after saline or TNF infusion. Zymosan, however, increased HMS activity only in endothelial cells from TNF-treated rats. Oxidation of palmitate or glutamine was not affected by TNF treatment either under basal conditions or after challenge in vitro. Our data indicate that, after phagocytosis in vitro or protein kinase C activation, glucose use and flux through the HMS increase in Kupffer cells. This is accompanied by increased glycolytic flux, with no changes in glucose oxidation in the tricarboxylic acid cycle. After TNF exposure, followed by a secondary stimulus, the enhanced glucose use by Kupffer cells is primarily channelled through the HMS pathway. These data suggest that the increased glucose use in vivo by Kupffer cells found after immune-stimulated conditions may subserve primarily the increased need for NADPH and HMS intermediates. Male Sprague-Dawley rats (300-340 g; Charles River,

Alterations of glucose metabolism and the oxidation of glutamine and palmitate were studied, by using specifically labelled substrates, in freshly isolated Kupffer cells and hepatic endothelial cells after infusion in vivo of human recombinant tumour necrosis factor-alpha (TNF; 7.5 x 10(5) IU/30 min per kg body wt., intravenously). Cells were incubated in a medium containing 5 mM-glucose, 0.4 mM-palmitate, 1 mM-lactate and 0.5 mM-glutamine. Administration of TNF in vivo increased glucose use in Kupffer cells by 70%. Glucose oxidation in the tricarboxylic acid cycle and flux in the Embden-Meyerhof (EM) pathway were elevated by 40 and 80% respectively. Treatment in vitro with 1 microM-phorbol 12-myristate 13-acetate (PMA) resulted in a similar percentage increase in glucose use by Kupffer cells prepared from either saline- or TNF-treated rats. However, PMA increased the activity of the hexose monophosphate shunt (HMS) by 3- and 10-fold in cells isolated from saline- or TNF-infused ani...

The development and proliferation of oval cells in experimental hepatocarcinogenesis induced by N- nitrosodiethylnitrosamine (NDEA) followed by carbon tetrachloride (CCl ) and in experimental hepatic fibrosis 4 induced by CCl were compared. Forty adult male Sprague-Daweley rats were subjected to two experiments: 1) 4 in hepatocarcinogenesis experiment, rats were treated with a single intraperitoneal injection of NDEA (200 mg/kg body weight), then, weekly, with subcutaneous injections of CCl (3 ml/ kg body weight/week) for 6 weeks and; 4 2) in hepatic fibrosis experiment, rats were treated with intraperitoneal injection of CCl (2 ml/kg body weight) 4 twice weekly for 3 months. Oval cells in the liver were identified by light microscopy, immunohistochemical expression of cytokeratin 19 and electron microscopy. In the hepatocarcinogenesis model, there was massive proliferation of oval cells, originated from the periportal area, forming ductules in between hepatocytes. In ultrathin sect...

Nitric oxide (NO) produced by inducible NO synthase (iNOS) mediates hypotension in endotoxemia. In this study, NO induction by a toxin-producing Streptococcus pyogenes isolate, H250, and by recombinant streptococcal pyrogenic exotoxin A (rSPEA) has been examined, both in vitro and in vivo. Streptococcal supernatants, but not rSPEA, induce production of nitrite by murine macrophages when both are coincubated with gamma interferon. Intraperitoneal injection of rSPEA did not cause significant production of NO. However, an elevated level of nitrate in serum was detected in a model of streptococcal fasciitis due to live H250. iNOS was localized to Kupffer cells, hepatocytes, and renal tubular cells by immunostaining. Administration of a NOS inhibitor, N G -monomethyl-L-arginine (L-NMMA), reduced peak concentrations of nitrate in serum but did not affect survival. NO is induced by H250, both in vitro and in vivo, mainly via SPEA-independent mechanisms. In this model, iNOS is expressed predominantly in the liver. Furthermore, in this model L-NMMA is not protective.

Mice deficient in both macrophage-colony-stimulating factor (M-CSF, op) and apolipoprotein E (apoE) have elevated cholesterol levels but are protected from atherosclerosis. To assess the contribution of macrophage (M) phenotypic heterogeneity and scavenger receptor (SR-A) expression to this seeming paradox, we characterized the M phenotype by immunohistochemistry in these animals. Lesion size was determined in animals fed a chow or Western-type diet, and lipoprotein clearance studies were performed in vivo. Op0/E0 mice have fourfold smaller aortic root lesions than op2/E0 animals despite 2.5-fold higher total plasma cholesterol levels. Ms in atherosclerotic lesions of op2/E0 mice constitute a predominantly recruited and M-CSF-dependent population. In addition, Ms in different locations in plaques show phenotypic heterogeneity. SR-A expression in op0/E0 mice is reduced in proportion to the decrease in M numbers, and M-CSF is thus not an essential requirement for SR-A expression in vivo. M-CSFdeficient mice degrade injected AcLDL , showing an adequate level of SR-A activity present in vivo. In contrast, ␤-VLDL clearance in op0/E0 mice is decreased, implicating monocytes/Ms in its catabolism. There is prominent lipid accumulation in op2/E0 Kupffer cells and hepatocytes but not in M-CSF-independent Kupffer Ms from op0/E0 mice. SR-A, while abundantly expressed on both Kupffer cells and sinusoidal endothelial cells in op2/E0 mice, remains mainly on sinusoidal endothelial cells in op0/E0 mice. This may explain preservation of SR-A activity in these animals. Our findings clearly illustrate the importance of both M-CSF and M-CSF-dependent monocytes/Ms in maintaining cholesterol homeostasis and in atherogenesis. (

The risk to wildlife from exposure to the explosive, 2,4,6-trinitrotoluene (TNT) has been a concern at numerous military installations where it has been found in the soil. To date, no published data are available describing effects of TNT exposure in an avian species. Subchronic dietary exposure to TNT was therefore evaluated in a species of management concern at military installations, the northern bobwhite (Colinus virginianus). Adult male and female quail (n ϭ 5/sex/dose) were given commercial feed containing 3,000, 1,500, 750, and 100 mg/kg TNT for 90 d following the determination of an acute lethal dose and a 14-d range finding study. Dietary TNT intake caused a dose-dependent decrease in total red blood cell counts, packed cell volume, total plasma protein, blood prolymphocytes, and blood lymphocytes. An increased trend in late apoptotic/necrotic blood leukocytic cells was also observed in TNT-exposed birds, as was hemosiderosis in the liver. With the exception of hemosiderosis, these trends were statistically significant yet of questionable biological significance. Since treatment-related responses in this preliminary study were variable, a conservative interpretation is suggested. However, since these treatments had concentrations that were a log-fold or more than doses in similar studies using mammals, these data suggest that northern bobwhite are less sensitive to oral exposures of TNT than mammals.

Induction of NF-kappaB-mediated gene expression has been implicated in the pathogenesis of alcoholic liver disease (ALD). Curcumin, a phenolic antioxidant, inhibits the activation of NF-kappaB. We determined whether treatment with curcumin would prevent experimental ALD and elucidated the underlying mechanism. Four groups of rats (6 rats/group) were treated by intragastric infusion for 4 wk. One group received fish oil plus ethanol (FE); a second group received fish oil plus dextrose (FD). The third and fourth groups received FE or FD supplemented with 75 mg. kg(-1). day(-1) of curcumin. Liver samples were analyzed for histopathology, lipid peroxidation, NF-kappaB binding, TNF-alpha, IL-12, monocyte chemotactic protein-1, macrophage inflammatory protein-2, cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), and nitrotyrosine. Rats fed FE developed fatty liver, necrosis, and inflammation, which was accompanied by activation of NF-kappaB and the induction of cytokines, c...

Telomere shortening controls the entry of cells into senescence. Functional expression of the telomerase catalytic subunit (human telomerase reverse transcriptase or hTERT) stabilizes telomere length and extends the life span of various normal human cells. Our aim was to assess the role of telomerase activity and telomere maintenance in regulating the proliferation of activated human hepatic stellate cells (HSCs), to establish an immortal human HSC cell line. Human HSCs were isolated from surgical specimens of normal liver and infected with a retrovirus expressing hTERT. Ectopic expression of hTERT reconstituted telomerase activity and maintained telomere length in human HSCs. Control human HSCs, which were either not infected or infected with a retroviral vector containing only the neomycin resistance gene, showed no detectable telomerase activity and had slightly shortened telomeres. These telomerase-negative HSCs entered a nondividing state after about 9 to 15 passages and senesced. In contrast, telomerase-positive HSCs to date have undergone 69 passages. Telomerase-positive HSCs did not undergo oncogenic transformation and exhibit morphologic and functional characteristics of activated HSCs. Microarray and RT-PCR analysis showed that mRNA expression patterns in telomerase-positive HSCs are very similar to those in activated human HSCs. Plating telomerase-positive HSCs on a basement membrane-like matrix reverts them toward a more quiescent phenotype. In conclusion, introduction of hTERT into activated human HSCs immortalizes them and maintains their activated phenotype. This newly developed cell line will be a useful tool to study the cell biology of human HSCs in culture. (Lab Invest 2002, 82:323-333).

Thyroid hormone (TH; 3,3,,5-triiodothyronine, T3) is required for the normal function of most tissues, with major effects on O2 consumption and metabolic rate. These are due to transcriptional activation of respiratory genes through the interaction of T3-liganded TH receptors with TH response elements or the activation of intermediate factors, with the consequent higher production of reactive O2 species (ROS) and antioxidant depletion. T3-induced oxidative stress in the liver triggers the redox upregulation of the expression of cytokines (tumor necrosis factor-α [TNF-α], interleukin-10), enzymes (inducible nitric oxide synthase, manganese superoxide dismutase), and anti-apoptotic proteins (Bcl-2), via a cascade initiated by TNF-α produced by Kupffer cells, involving inhibitor of κB phosphorylation and nuclear factor-κB activation. Thus, TH calorigenesis triggers an expression pattern that may represent an adaptive mechanism to re-establish redox homeostasis and promote cell survival...

L-3,3′,5-triiodothyronine (T3) 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 (GdCl3; 10 mg/kg i.v. 72 h before T3[0.1 mg/kg i.p.]) or NADPH oxidase inhibitor apocynin (1.5 mmol/L added to the drinking water for 7 days before T3), and determinations were performed 2 h after T3. T3increased 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 GdCl3treatment prior to T3, an agent-eliciting Kupffer-cell depletion, inhibition of colloidal carbon phag...

Thyroid hormone (3,3V,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-nB thus up-regulating gene expression. T 3 elicits an 80-fold increase in the serum levels of tumor necrosis factor-a (TNF-a), which is abolished by pretreatment with the antioxidants a-tocopherol and N-acetylcysteine, the Kupffer-cell inactivator GdCl 3 , or an antisense oligonucleotide against TNF-a. In addition, T 3 treatment activates hepatic NF-nB, a response that is (i) inhibited by antioxidants and GdCl 3 and (ii) accompanied by induced mRNA expression of the NF-nB-responsive genes for TNF-a and interleukin (IL)-10. T 3 also increases the hepatic levels of mRNA for IL-1a and those of IL-1a in serum. Up-regulation of liver iNOS expression is also achieved by T 3 , through a cascade initiated by TNF-a and involving InB-a phosphorylation and NF-nB activation. In conclusion, T 3 -induced oxidative stress in the liver enhances the DNA-binding of NF-nB and the NF-nB-dependent expression of cytokines and iNOS by actions primarily exerted at the Kupffer cell level.

Protracted liver assault results in hepatic fibrosis, frequently advancing into cirrhosis, hepatic failure, portal hypertension and hepatocellular carcinoma or degeneration. Hepatic fibrosis emanates from the wound-healing response of the liver to persistent assault. Following acute liver insult, such as viral hepatitis, parenchymal cells regenerate and substitute the necrotic or apoptotic cells. A salient proportion of the affected population of NAFLD advances to nonalcoholic steatohepatitis, NASH, and is characterised by inflammation, hepatocellular swelling, with ensuing eruption of deteriorating fibrosis. An untreated or persistent NASH can progressively culminate in liver cirrhosis and hepatocellular carcinoma. Chronic liver derangement results in pathologic ECM protein or liver fibrosis aggregation. In essence, the encompassing characterisation of human ECM molecular composition provides for excursions into mechanisms of liver disease or hepatocellular degeneration. Hepatocytes are characterized by elevated mitochondrial concentrations. The difference between NASH and fibrosis is evident that the progression of NASH to cirrhosis commences as inflamed liver tissue evolves into scar tissue or fibrosis that is capable of obliterating the liver from optimum functionality. A third or more of persons presenting with NASH develop cirrhosis , and also elevates and accelerates the risk in the development of liver cancer. The hepatic stellate cells are responsible for liver fibrosis as they are substantially involved in the initiation, progression, and regression of liver fibrosis via the secretion of fibrogenic factors which promote portal fibrocytes, fibroblasts, and bone marrow-derived myofibroblasts in the formation of collagen, and consequential propagation of fibrosis.

We examined the effects of several hemopoietic growth factors on proliferation of rat liver macrophages in &FO. The proliferative response of liver macrophages to hemopoietic growth factors was assayed on the basis of [methyl-'Hlthymidine uptake. Macrophage colony-stimulating factor and recombinant murine granulocyte-macrophage colony-stimulating factor stimulated [rnethyl-'H]thymidine incorporation in a concentration-dependent manner. With granulocyte-macrophage colony-stimulating factor, maximum incorporation was observed at 50 U/ml, whereas with macrophage colony-stimulating factor no incorporation plateau was observed up to 50% L929-conditioned medium. Incubation of liver macrophages with various concentrations of recombinant human interleukin-2, recombinant murine interleukin-3 and recombinant human interleukin-6 or culture medium alone did not result in significant incorporation of [methyl-SHlthymidine. When liver macrophages were fractionated according to cell size, highest incorporation was observed in the large macrophages. Proliferating cells in cultures of all subfractions were microscopically identified as typical macrophages by the use of macrophage-specific monoclonal antibodies. After 6 days in culture, these macrophages had functional properties similar to those of resident liver macrophages with respect to phagocytosis and in U ~~F O activation with immunomodulators to tumorcytotoxicity and secretion of nitric oxide and tumor necrosis factor-a. These results suggest that macrophage colony-stimulating factor and granulocyte-macrophage colony-stimulating factor play important roles among the regulatory factors that support local proliferation of rat liver macrophages. (HEPATOLOGY 1994;