Study of secretome deregulation of a rat model of endotoxemic shock using a non-targeted mass spectrometry approach

Abstract

The secretome is a set of proteins secreted by a cell at a given time and under certain conditions. The secretome, easily accessible from plasma and analyzable by a proteomic approach, represents a good opportunity to identify biomarkers in septic shock. This pathology corresponds to a systemic inflammatory response syndrome related to an infection and associated with cardiocirculatory failure leading to organ dysfunction with a mortality rate of 40%. The identification of diagnostic/prognostic biomarkers is crucial to improve patient outcome. Study the secretome of a rat model of endotoxemic shock to identify relevant deregulated proteins (DEP). Endotoxemic shock was induced by lipopolysaccharides injection (LPS, S. enterica typhi, 0.5 mg/kg, iv) and compared to controls (Ringer lactate, iv). Under isoflurane anesthesia, carotid cannulation allowed evaluation of mean arterial blood pressure (MAP), heart rate and blood sampling (T0, and T50 or T90 min on EDTA and protease inhibitor). Plasma was analyzed with tandem MS based on a label free quantification. Gene ontology (GO) analyses defined several groups of biological process (BP) in which the DEP were involved. Ninety minutes after shock induction, the LPS group present a reduction in MAP (−45%, P < 0.05) and increased lactate levels (+27%, P < 0.05). Proteomic analyses revealed 6 and 22 DEP, such as Ribonuclease 4, in the LPS group respectively at T50 and T90. At T50 and T90 Go-BP show common alterations in response to oxidative stress, tissue remodeling and coagulation. This study proposes an approach to identify DEP in septic shock. DEP need to be tested in cellular models in order to understand their role in the physiopathology of shock and to improve understanding of adaptations of the secretome during sepsis. The link between our results and patient prognosis will need to be studied for clinical use.