Kozlov 2013 Abstract MiP2013
|Kozlov AV, Paier-Pourani J, Weidinger A, Dungel P, Redl H, Duvigneau C (2013) Regulatory role of mitochondrial ROS upon inflammation. Mitochondr Physiol Network 18.08.|
Mitochondrial reactive oxygen species (mtROS), considered earlier as a harmful by-product of mitochondrial respiration, have been recognized as an important component of intracellular signalling cascades. This study aimed to clarify the impact of mtROS on cellular dysfunction induced by inflammation.
We used an in vivo model of systemic inflammatory response induced by LPS in rats and an in vitro model of hepatocytes cultured with inflammatory mediators (IM) that were obtained by incubation of white blood cells with LPS. MitoTempo, a mitochondria targeted antioxidant, was used to clarify the effects of mtROS on mitochondrial function, the ER stress response, and cell damage (ALT, AST). The maximal concentration of mitoTEMPO, which does not disturb mitochondrial function, was determined as 500 nmol/l, and was therefore used in the experiments. The levels of ROS and nitric oxide (NO) were determined using spin and fluorescent probes. Gene expression was examined by RT-PCR and Western Blot analysis. Respiratory function of mitochondria was determined by high-resolution respirometry.
In vivo, LPS increased the levels of liver dysfunction markers (ALT and AST) and the levels of NO-Hb complexes in blood, but changes in the respiratory function of mitochondria were very modest. MitoTEMPO significantly reduced the levels of ALT, AST and Hb-NO in animals receiving LPS. A possible functional connection between mtROS, NO and hepatocyte dysfunction was examined in in vitro experiments. Using mitoTEMPO and a specific inhibitor of NO synthase, we showed that hepatocytes exposed to IM build up a feed-forward mtROS-iNOS cycle which drops mitochondrial potential due to oxidative damage of mitochondrial membranes (for details see MiP2013 abstract by Paier-Pourani). Simultaneously, mtROS upregulated genes involved in inflammatory response and downregulated genes involved in unfolded protein response (GRP78).
Our data suggest that inflammation mediated elevation of mtROS in liver cells reduce membrane potential without significant impairment of mitochondrial function. In addition ROS amplify inflammatory gene expression, and inhibit unfolded protein response and thereby prevent the recovery of major liver functions. Further studies are required to clarify pathophysiological relevance of these three pathways.
• O2k-Network Lab: AT Vienna Kozlov AV
Labels: MiParea: mt-Membrane, nDNA;cell genetics, mt-Medicine Pathology: Sepsis Stress:Oxidative stress;RONS Organism: Rat Tissue;cell: Liver Preparation: Intact cells, Isolated mitochondria
Regulation: mt-Membrane potential
1 - Ludwig Boltzmann Institute for Experimental and Clinical Traumatology; Research Centre of AUVA, Vienna, Austria;
2 - Institute of Medical Biochemistry, Department of Biomedical Sciences, University of Veterinary Medicine, Vienna, Austria.