Effects of normocaloric vs. hypocaloric enteral nutrition on whole-body protein turnover in critically ill patients

Organ failure is the main cause of mortality in critically ill patients treated in the ICU. The overall aim of this project is to elucidate the role of an impaired protein breakdown of damaged proteins by a block in the autophagy flux in the development of organ failure. We have developed a model for measuring autophagy flux that allows for screening of larger patients groups. The first results with this novel model suggest that there are factors in the blood of critically ill patient that can induce a block in autophagy. The specific aims of the project are to assess where in the autophagy pathway the block occurs, what in blood actually causes the block and what the cellular and physiological consequences of this block are. For this we will incubate primary human muscle cells and hepatocytes with serum from 100 critically ill patients and measure autophagy flux by in-cell western blotting and formation of the different stages in the autophagy pathway with confocal microscopy. We will use proteomics and metabolomics analyses to find the factors in serum that induce a block in the autophagy flux. To measure the cellular and physiological consequences of a block we will measure formation of damaged mitochondrial proteins and mitochondrial function. Within the project we will identify factors in the blood of critically ill patients with organ failure that can induce a block in autophagy. In addition we will find out if nutrition has a possible worsening effect on this.