The most important and novel finding of this work was enhanced liver Kupffer cell phagocytic and metabolic function by hypervitaminosis A. An animal model of hypervitaminosis A was developed in male Sprague-Dawley rats gavaged with 250,000 I.U. retinol/Kg body weight/day for 3 weeks. Presence of hypervitaminosis A was indicated by characteristic changes in the fur coat, presence of brittle bones and spontaneous fractures and a significant increase in plasma and liver concentrations of retinyl palmitate while retinol levels remained the same as in controls. Hypervitaminosis A did not cause severe liver abnormalities as reflected by normal plasma glutamate pyruvate transaminase activity and bilirubin. Hepatic blood flow and portal pressure were also normal. Liver microsomal cytochrome P-450 was decreased while malondialdehyde, a by-product of lipid peroxidation, was increased by the Vitamin A treatment. Examination of liver tissue by light microscopy showed no signs of liver cell injury. The main change was a marked increase in size of the fat or Vitamin A storing cells. Although hypervitaminosis A itself did not cause severe liver damage, pretreatment with high doses of Vitamin A severely potentiated liver injury by known hepatotoxicants such as carbon tetrachloride, endotoxin and acetaminophen. The potentiation of hepatotoxicity was determined by activity of glutamate pyruvate transaminase in plasma as well as by histological examination of liver tissue. Measurement of clearance from blood of indocyanine green and ⁹⁹ᵐTc-disofenin indicated this hepatocyte function was normal. Kupffer cell phagocytic function was enhanced in hypervitaminosis A as determined by clearance from blood of ⁹⁹ᵐTc-sulfur colloid. In vitro, there was also evidence that treatment with high doses of Vitamin A activated or enhanced Kupffer cell function. Kupffer cells from control and Vitamin A treated rats were isolated by enzymatic dispersion, purified by centrifugal elutriation, and placed in culture. Activation was indicated by (1) increased phagocytosis of ⁵¹Cr-labeled opsonized sheep red blood cells (2) enhanced release of superoxide anion and (3) enhanced production of tumor cytolytic factor by Kupffer cells from Vitamin A treated rats. Stimulation of Kupffer cell function in hypervitaminosis A seemed to be via lymphokines produced by lymphocytes in response to the excess Vitamin A. We propose that activated Kupffer cells may play an important role in liver injury in hypervitaminosis A.

Gene therapy can potentially treat a wide range of diseases ranging from inherited diseases to cancer. The successful use of nucleic acids to treat genetic diseases is limited by rapid capture and degradation of the nanoparticle by Kupffer cells in the liver. Scavenger receptors on the cell surface, capture both viral and non-viral nanoparticles leading to reduced efficacy. PEG-peptides were found to inhibit scavenger receptors on the surface of Kupffer cells by forming albumin nanoparticles when intravenously dosed. This work explores the development of potent, low-molecular weight PEG-peptide inhibitors. In order to study the in vivo activity of the nanoparticle, an in vivo assay was developed to directly assess the potency of inhibition. High molecular weight polylysine peptides (33.5 kDa) inhibited liver uptake with an IC50 of 18 μM. Incorporation of four leucine residues, to improve albumin binding, allowed for a decrease in PEG molecular weight and number of lysine residues, resulting in PEG5kda-Cys-Tyr-Lys-(Leu-Lys4)3-Leu-Lys (7.4 kDa) that inhibited scavenger receptors with an IC50 = 20 μM. Further decrease in the PEG molecular weight resulted in the discovery of PEG2kDa- Cys-Tyr- (Leu-Lys4)3-Leu-Lys (4.4 kDa) with potency of 3 μM. The increase in potency could be attributed to a decrease in the zeta potential of the albumin nanoparticle resulting in more efficient scavenger receptor mediated uptake. Co- administration of PEG2kDa- Cys-Tyr-(Leu-Lys4)3-Leu-Lys with a stable PEGylated polyacridine DNA polyplex resulted in inhibition of rapid polyplex uptake by the liver with an IC50 = 11 μM. Other properties including spatial distribution of leucine, hydrophobicity and peptide length were also explored to determine their effect on liver uptake. Hydrophobic peptides resulted in the formation of micelles which were inactive as scavenger receptor inhibitors and exhibited increased liver uptake upon dose escalation. Reduction in the peptide length resulted in peptides that were not captured by the liver. Inhibition scavenger receptors has the potential to improve the efficacy of viral and non-viral nanoparticles. The findings of this work provide a framework for the development of PEG-peptide inhibitors capable of blocking live uptake of viral and non-viral nanoparticles.

Thesis (Ph.D.)--University of Western Australia, 2005.

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第18896号 / 医博第4007号 / 新制||医||1009(附属図書館) / 31847 / 京都大学大学院医学研究科医学専攻 / (主査)教授 坂井 義治, 教授 伊達 洋至, 教授 前川 平 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DGAM

Les adénovirus (Ad) sont parmi les vecteurs les plus utilisés en thérapie génique. Cependant, les données d’essais pré-Cliniques et cliniques ont montré qu’ils induisaient une forte toxicité hépatique consécutive à leur tropisme hépatique, une réponse inflammatoire et une forte thrombocytopénie. Différents travaux avaient montré que l’interaction de l’Ad avec le facteur de la coagulation X (FX).était responsable de la transduction in vivo des hépatocytes après administration systémique des vecteurs Ad. Cependant, des résultats précédents du laboratoire avaient montré également que le pseudotypage d’une autre protéine de capside, la fibre, permettait de réduire la transduction hépatique. Dans le but de mieux comprendre le rôle de la fibre dans le tropisme et la toxicité des Ad, nous avons comparé des Ad recombinants pseudotypés pour tout (tige et tête de la fibre : AdF3) ou partie (tige : AdS3K5) de la fibre Ad3 avec un Ad5 à capside non modifiée (Adwt). Après administration systémique chez la souris, l’AdF3 et l’AdS3K5 induisent une plus faible expression du transgène dans le foie et la rate comparativement à l’Ad5wt. Cette réduction ne résulte ni d’un défaut de capture de ces vecteurs dans le foie ni de leur incapacité à utiliser le FX. Cependant, nos résultats ont révélé que les Ad pseudotypés par la fibre Ad3 étaient capturés de façon plus importante par les cellules de Kupffer. Nous avons montré que cette capture était une propriété intrinsèque de la fibre Ad3 puisqu’elle était observée également après administration systémique d’un Ad de sérotype 3. De façon intéressante, les Ad pseudotypés par la fibre Ad3 restent capables de transférer des gènes dans les tumeurs aussi efficacement que l’Adwt.Dans la deuxième partie de nos travaux, nous avons cherché à mieux comprendre les mécanismes de la thrombocytopénie consécutive à l’administration d’Ad. Nous avons défini la cinétique de la thrombocytopénie ainsi que l’effet de la dose virale. Nous avons montré que certains facteurs de l’hôte comme les facteurs de la coagulation ou la rate n’étaient pas impliqués dans la thrombocytopénie. De façon intéressante, nous avons montré que la fibre Ad5 jouait un rôle dans l’induction de la baisse plaquettaire puisque l’administration des virus à fibre Ad3 n’induisait plus de forte baisse plaquettaire. Parallèlement, nous avons observé un profil inflammatoire associé à l’administration des Ad à fibre modifiée beaucoup plus réduit que celui de l’Adwt. Nos travaux en cours évaluent l’existence possible d’une corrélation entre la production de cytokines/chimiokines et la thrombocytopénie.L’ensemble de ces résultats montre que le pseudotypage des Ad5 par la fibre de l’Ad3 permet de réduire leur toxicité et de limiter la réponse inflammatoire tout en conservant un transfert de gènes efficace dans les tumeurs. L’introduction de ce type de modification de capside dans les Ad oncolytiques devrait permettre de conserver leur capacité à se répliquer dans les tumeurs tout en limitant les toxicités liées à leur dissémination par voie systémique. / To date adenoviruses (Ad) are the most used vectors in gene therapy. However, Ad use is hampered by a strong liver tropism that leads to hepatotoxicity, a strong inflammatory response and the induction of thrombocytopenia. Binding of Ad hexon to coagulation factor X (FX) is responsible for hepatocyte transduction in vivo. As a consequence, mutation of hexon protein abrogates Ad interaction with FX and reduces liver transduction. However, previous results of our lab have demonstrated that Ad5 pseudotyping with fiber Ad3 also resulted in significant reduction of liver transduction. To understand how fiber modification affects in vivo Ad tropism, we used two pseudotyped viruses with whole (AdF3) or only the shaft (AdS3K5) of Ad3 fiber.Following systemic delivery of fiber-Modified Ads, a reduced transduction was observed 2 days p.i. in liver and spleen. This reduction was not due to the impairment of fiber-Modified Ads liver entry or FX use in vivo. Remarkably, after Kupffer cells depletion, a restored transgene expression level was observed, suggesting that fiber-Modified Ads are strongly uptaken by Kupffer cells. We have demonstrated that this strong uptake is an Ad3 intrinsic property since Ad3 was also strongly uptaken by Kupffer cells. Interestingly, fiber-Modified Ads transduce tumours as efficiently as Ad5. In the second part of this work, we aimed to better understand the mechanism of Ad-Induced thrombocytopenia. We first defined the kinetic and dose-Dependence of Ad-Induced thrombocytopenia. Then, we have shown that factors of the host such as the coagulation factors and the spleen were not involved in the thrombocytopenia development. Interestingly, we demonstrated o role for Ad5 in this platelet count reduction since fiber-Modified Ad induced only a modest thrombocytopenia. In parallel, we have observed a reduced production of inflammatory cytokine and chemokine following fiber-Modified Ad administration. Experiments are ongoing to investigate a possible correlation between inflammatory responses and thrombocytopenia. Altogether, our findings demonstrate that Ad5 pseudotyping with Ad3 fiber allows à reduced toxicity and inflammatory response while tumour transduction efficacy is remained. Therfore, oncolytic Ad pseudotyped with Ad3 fiber might be potent tool in tumor virotherapy while limiting risk of toxicity.

Polychlorinated biphenyls (PCBs) are ubiquitious lipophilic environmental pollutants. At least some of the PCB congeners and mixtures are hepatic tumor promoters. The mechanisms are not fully understood and might be multifactorial Besides being the most abundant congener in the environment, 2,2,4,4,5,5-hexachlorobiphenyl (PCB-153), has been previously shown to increase hepatocyte proliferation 48h after exposure in rats. The goal of this study was to determine whether hepatic Kupffer cells are important in the promoting activity of PCBs. The hypothesis of this study was that modulation of Kupffer cell activity by PCBs may contribute to PCB-induced liver tumor promotion. The experimental approach consisted on three in vivo models (tumor promotion model and two short term exposure models) and one in vitro model. In the tumor promotion model, glycine inactivation of Kupffer cells did not significantly influence the promoting activity of PCB-77 (3,3,4,4-tetrachlorobiphenyl) or PCB-153. For the short term exposure model, we investigated the effect of Kupffer cell inactivation by glycine and the effect of Kupffer cell depletion on PCB-153s impact on hepatocyte proliferation. The oil used as a vehicle had no significant effect on any of the end points considered. Inhibition of Kupffer cells with glycine or the absence of Kupffer cells did not affect cell proliferation or NF-B activation after PCB treatment compared to the control. In vitro, PCB-153 increased DNA binding activity of NF-B in Kupffer cells but did not significantly increase the TNF- concentration in the medium. In conclusion, PCB-153 increased the number of preneoplastic foci per liver in the casein group but had no significant effect on cell proliferation, and Kupffer cells do not seem to play a role in hepatocyte proliferation.

[Truncated abstract] Chronic liver injury results from many etiologies ranging from viral infection to inborn errors of metabolism. A common result of liver injury is activation of hepatic stellate cells and portal fibroblasts to myofibroblasts. In chronic injury, production of extracellular matrix by activated myofibroblasts results in liver fibrosis and ultimately cirrhosis. Kupffer cells and monocytes may play an important role in the pathogenesis of certain liver diseases. Endotoxin-responsive macrophages and recruited monocytes (CD14-positive cells) are potential sources of profibrogenic factors but their potential role in the pathogenesis of liver disease has not previously been examined. The first aim of this thesis described in chapter 3 was to evaluate the hypothesis that CD14-positive macrophages/monocytes are present in the livers of patients with hereditary haemochromatosis (HH), primary biliary cirrhosis (PBC), chronic hepatitis C (HCV) and nonalcoholic steatohepatitis (NASH) and contribute to the pathogenesis of fibrosis as evidenced by co-localization of these cells with activated myofibroblasts. Liver specimens from control subjects and those with HH, PBC, HCV and NASH were immunostained for CD14, CD68 and α-smooth muscle actin and the number of cells expressing these antigens was determined. The total number of hepatic CD68-positive cells was similar in diseased and control livers. The number of CD14-positive cells correlated with advanced fibrosis in HH, PBC, HCV but not in NASH. The number of CD14-positive cells was increased with advanced inflammatory activity in HCV. CD14-positive cells were often associated with α-smooth muscle actin-positive myofibroblasts in fibrous septa. In conclusion, many forms of human chronic liver disease demonstrate increased numbers of CD14-positive macrophages/monocytes which are associated with fibrous septa and myofibroblasts. To determine whether CD14-positive cells contribute to fibrogenesis, experimental models of liver injury were used in chapters 5 and 6. The aim of chapter 5 was to determine whether CD14-positive macrophages/monocytes are detected in a bile duct ligation model of liver injury. To accomplish this aim, a novel antibody to rat CD14 was developed as described in chapter 4. A time-course study was undertaken in rats following bile duct ligation for up to 14 days. An increase in the number of hepatic CD14-positive cells was detected early following bile duct ligation, and was associated with increased gene expression of α-smooth muscle actin and procollagen I. Thus, myofibroblastic transformation in this model was associated with increased numbers of CD14-positive cells suggesting a possible relationship between the two phenomena. In order to specifically evaluate the role of CD14 in myofibroblastic transformation, a final study in CD14 knockout (KO) mice was undertaken in chapter 6

Partial hepatectomy (PH) is a treatment of choice for patients suffering from early stage hepatocellular carcinoma (HCC). Ablation of large proportion of the liver is rendered possible because of the ability of the liver to regenerate. Yet, a significant number of patients will experience recursion of the disease. Such relapses are unfortunately rather frequent and constitute a bad prognosis. The development of new strategies aiming at reducing the risk of recursion of HCC is thus a paramount element of the surgery-based treatment. Some previous studies have proposed that the regenerative process as well as the fate of the immune cells during the liver regeneration process is linked to this recurrence phenomenon.In this study, we investigated the impact of PH on HCC development in a pre-clinical murine model. We implanted Hepa1-6 hepatocarcinoma cells (a murine hepatocarcinoma cell line) directly in the liver of mice and compared a non-resected group with a group undergoing 40% PH one week following tumor implantation. Analysis were relying on bioluminescence imaging and flow cytometry. We demonstrated that liver regeneration increases tumoral proliferation. This proliferation was associated with a reduction in the number of liver resident macrophages, i.e. Kupffer cells (KC). KC anti-tumoral activity was also proved using conditional ablation model. We further studied the mechanisms leading to this disappearance and demonstrated that, under normal regeneration conditions, PH-induced KC number reduction was dependent on tumor necrosis factor-α (TNF-α), receptor interacting protein kinase (RIPK) 3 and caspase-8 activation whereas interleukin (IL)-6 acted as a KC pro- survival signal. In mice with previous Hepa 1-6 encounter, the KC reduction changed toward a TNF-α-RIPK3-caspase-1 activation. This data suggest a switch from apoptosis to pyroptosis induction in KC following PH. Moreover, KC disappearance associated with caspase-1 activity induced the recruitment of monocyte derived cells that are beneficial for tumor growth while caspase-8 dependent reduction did not, underlying the importance of macrophages activated death-pathway in regulating the anti-tumoral immune response. Our results show the necessity for comprehensive multidisciplinary treatment approach following PH and propose new targets in order to reduce the relapse of the disease occurring after surgery. / Doctorat en Sciences biomédicales et pharmaceutiques (Médecine) / info:eu-repo/semantics/nonPublished

No description available.

Les hépatopathies métaboliques regroupent les maladies non alcooliques du foie (NAFLD) et les maladies alcooliques du foie (MAF) causées respectivement par l’obésité ou une consommation excessive d’alcool. Ces pathologies vont de la simple stéatose à des formes aggravées pouvant aller jusqu’au carcinome hépatocellulaire. D’autres facteurs que le surpoids ou l’abus d’alcool jouent un rôle dans la susceptibilité des patients à développer une NAFLD ou une MAF. Cette thèse a pour objectif de clarifier et d'étudier les mécanismes et les facteurs participant à l’installation de l’inflammation dans ces deux pathologies. Mes travaux ont porté d’une part sur le rôle de la cellule de Kupffer dans les étapes précoces de la NAFLD et d’autre part sur l’étude du microbiote intestinal comme cofacteur déclenchant de la MAF. La cellule de Kupffer lors de la stéatose, étape précoce de la NAFLD, présente une dérégulation de son homéostasie lipidique qui participe à son phénotype pro-inflammatoire et favorise l’inflammation hépatique. L’impact du fructose, largement utilisé dans notre alimentation actuelle, a été étudié et aggrave l’inflammation hépatique lors d’un régime hyperlipidique et ceci est associé à une dysbiose spécifique. Dans la MAF, une dysbiose intestinale, une diminution des Bacteroides, a été associée aux lésions hépatiques dans un modèle murin d’alcoolisation. L‘utilisation de traitements permettant de maintenir cette population à des taux élevés a corrigé cette dysbiose et protégé les animaux face aux lésions hépatiques. Ces travaux permettent d‘envisager le MI comme une cible prometteuse permettant de contrôler l’évolution des hépatopathies métaboliques vers des formes sévères. / Metabolic hepatopathies is including Non Alcoholic Fatty Liver Disease (NAFLD) and Alcoholic Liver Disease (ALD) due to an excessive consumption of alimentation or alcohol. The pathologies range from simple steatosis to aggravated forms until hepatocellular carcinoma. Other factors than overweight or alcohol abuse play a role in sensitivity of patients to develop NAFLD or ALD. The aim of this thesis is to clarify and study the mechanisms and factors that lead to the installation of inflammation in those pathologies. My work covered in part on the role of Kupffer cell in the early stages of NAFLD and secondly on the study of intestinal microbiota as a cofactor triggering the MAF.The Kupffer cell role in steatosis, the early stages of NAFLD, showed a deregulation of its lipid homeostasis involved in the pro-inflammatory phenotype and promotes liver inflammation. The impact of fructose, widely used in our current diet, was studied and worsening liver inflammation during high fat diet. This is associated with a specific dysbiosis. In ALD, intestinal dysbiosis, a decrease of Bacteroides, leading to liver damage has been established. The use of treatments to maintain this population with high levels corrected the dysbiosis and has protected animals against liver damages. Both works on the NAFLD and ALD establish MI is a promising target to control the evolution of metabolic liver diseases toward aggravated forms.