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See detailDisruption in energy metabolism and mitochondrial function in a cellular model of inflammation-induced acute kidney injury
Quoilin, Caroline ULg; Mouithys-Mickalad, Ange ULg; Lécart, Sandrine et al

Poster (2013, September)

Sepsis is a very complex clinical condition characterized by stimulation of a systemic inflammatory response due to an infection. It has a profound deleterious effect on kidney functions leading to sepsis ... [more ▼]

Sepsis is a very complex clinical condition characterized by stimulation of a systemic inflammatory response due to an infection. It has a profound deleterious effect on kidney functions leading to sepsis-induced acute kidney injury (AKI). This failure seems to occur through complex mechanisms involving the immune system response, inflammatory pathways, cellular dysfunction and hemodynamic instability. To study the role of cellular energetic metabolism dysfunction and mitochondrial impairment in the occurrence of AKI during sepsis, we developed an inflammation-induced in vitro model using proximal tubular epithelial cells (HK-2) exposed to a bacterial endotoxin (lipopolysaccharide, LPS). This investigation has provided key features on the relationship between endotoxic stress and mitochondrial respiratory chain assembly defects. Firstly, we have shown that renal cells subjected to LPS are no longer capable to use adequately the available oxygen to maintain their metabolic functions. One hypothesis of this down-regulation suggests that impairment in mitochondria oxidative phosphorylation could prevent cells from using oxygen for adenosine triphosphate (ATP) production and potentially could cause sepsis-induced organ failure. Our study has then investigated this possible mitochondrial impairment to explain the decreased O2 consumption rate observed in LPS-treated HK-2 cells. After exposure to LPS, functionality of mitochondria was affected without any disturbance in their spatial organization. LPS seemed rather to interrupt mitochondrial oxidative phosphorylation by blocking cytochrome c oxidase activity. As a consequence, disruptions in the electron transport and the proton pumping across the system occurred, leading to a decrease of the mitochondrial membrane potential, an electron leakage as the form of superoxide anion, a release of cytochrome c in the cytosol and a decrease in ATP production. This irreversible defect in the production of cellular energy would support the concept that kidney failure in sepsis may occur on the basis of cytopathic hypoxia. [less ▲]

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See detailAn ESR, Mass Spectrometry and Fluorescence microscopy approach to study the stearic acid derivatives anchoring in cells
Grammenos, Angeliki ULg; Fillet, Marianne ULg; Collodoro, Mike et al

in Applied Magnetic Resonance (2012)

Lateral phase separations in biological membranes are of great interest, making Electron Spin Resonance (ESR) spectroscopy combined with spin labelling a non destructive and sensitive technique for the ... [more ▼]

Lateral phase separations in biological membranes are of great interest, making Electron Spin Resonance (ESR) spectroscopy combined with spin labelling a non destructive and sensitive technique for the study of lipid rafts. This is currently accepted that spin probe localization is on the plasma membrane. However, no study confirms this hypothesis. Herein, we report, for the first time, an accurate multi spectral method for the quantification of lipid spin label presence in every sub-cellular fraction. Cells were incubated with 5-doxyl stearic acid derivative and then sub-fractionated. Results of our multimodal spectroscopy approach ubiquitously demonstrate that the presence of ESR spin label only sets in the plasma membranes. [less ▲]

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