Effects of human serum albumin on TNFα-induced cell death and mitochondrial dysfunction in the liver cells
[eng] Albumin exerts pleiotropic actions beyond its oncotic power, which include binding, transport and detoxification of endogenous and exogenous molecules, antioxidant activity and the modulation of immune and inflammatory responses. In particular, recent studies have shown that albumin reduces th...
| Autor: | |
|---|---|
| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2023 |
| País: | España |
| Institución: | Universidad de Barcelona |
| Repositorio: | Dipòsit Digital de la UB |
| OAI Identifier: | oai:diposit.ub.edu:2445/197300 |
| Acceso en línea: | https://hdl.handle.net/2445/197300 http://hdl.handle.net/10803/688155 |
| Access Level: | acceso abierto |
| Palabra clave: | Malalties del fetge Cirrosi hepàtica Cèl·lules hepàtiques Albúmines Mitocondris Mort cel·lular Liver diseases Hepatic cirrhosis Liver cells Albumins Mitochondria Cell death |
| Sumario: | [eng] Albumin exerts pleiotropic actions beyond its oncotic power, which include binding, transport and detoxification of endogenous and exogenous molecules, antioxidant activity and the modulation of immune and inflammatory responses. In particular, recent studies have shown that albumin reduces the production of cytokines in leukocytes. In the first study we investigate whether albumin has the ability to protect tissues against the damaging actions of inflammatory mediators. We limited our investigation to tumor necrosis factor (TNF)α, which exemplifies the connection between immunity and tissue injury. Cytokine-induced inflammation and mitochondrial oxidative stress are key drivers of liver tissue injury. In the second study, we model liver inflammatory conditions, to explore whether this protein plays a role in hepatocyte mitochondrial preservation against the damaging actions of the cytotoxic cytokine TNFα. The hypothesis of the present thesis is that albumin protects liver cells against immunopathology and mitochondrial dysfunction induced by the pleiotropic cytokine TNFα, leading to tissue homeostasis and preventing organ dysfunction present in advanced liver disease. In vivo experiments in analbuminemic mice demonstrate that these mice exhibit a more pronounced response to a TNFα liver injury model induced by LPS+ D-gal administration. Tissue protective action against LPS+D-gal liver injury is also observed during administration of human albumin to humanized mice (hAlb+/+/hFcRn+/+) with CCl4-induced pre-established early cirrhosis. The cytoprotective actions of albumin against TNFα-induced injury are confirmed ex vivo, in PCLS, and in vitro, in primary hepatocytes in culture. The protective actions of albumin are independent of its scavenger and oncotic properties, and are reproduced using recombinant human albumin expressed in Oryza sativa. Cytoprotection of albumin against TNFα injury is related to inhibition of lysosomal cathepsin B release accompanied by reduction of mitochondrial cytochrome c release and caspase-3 activity. Transmission electron microscopy analysis reveals that in the absence of albumin, hepatocytes are more susceptible against the damaging actions of TNFα and show more round-shaped mitochondria with fewer intact cristae than hepatocytes cultured with albumin. In the absence of albumin in the cellular environment, hepatocytes also show increased mitochondrial ROS generation and fatty acid oxidation. Protective actions of albumin on mitochondria against TNFα damage is associated with restoration of an isocitrate-α-ketoglutarate breakpoint in the tricarboxylic acid cycle and regulation of antioxidant transcription activator factor 3 (ATF3). The involvement of ATF3 in the protective actions of albumin against cytokine-induced mitochondrial dysfunction is confirmed in vivo in mice with LPS/D-gal-induced liver injury. In the first study, our results demonstrate the ability of albumin to protect hepatocytes against the cytotoxic effects of the cytokine TNFα. These protective actions of albumin are carried out through the inhibition of the leakage of cathepsin cysteine protease B from the lysosomes, accompanied by a reduction in the release of cytochrome c from the mitochondria. In the second study, our data provide in vitro, ex vivo, and in vivo evidence for the essential role of albumin in preserving liver cell mitochondria against the damaging actions of TNFα. Taken together, our data highlight the importance of maintaining albumin levels within the normal range not only in the intravascular compartment but also in the extravascular and interstitial space, especially in conditions of advanced liver disease in which hypoalbuminemia is common. |
|---|