Role of the Lectin-like Domain of Thrombomodulin in Murine Sepsis-Induced Cardiac Depression
Acronym: Thrombomodulin
Principal Investigator: PD. Dr. med. Sebastian Stehr
Team: M. sc. Nadine Hechaichi, Dipl.-Ing. Jacqueline Fischer (FH)
Research Area: D Sepsis related Organ Failure
Project Number: D1.10
Duration: 01.07.2011 - 31.06.2014
Module: Senior Research Group
The Problem
Cardiac depression is observed as a feature of sepsis and is related with a poor outcome. The project aims to unravel molecular mechanisms of cardiac failure in dependence of Thrombomodulin as well as the interactions of Thrombomodulin with HMGB1 as a potential ligand.
Results so far
In preliminary experiments we saw a strong indication of a pivotal role of the lectin-like domain of thrombomodulin (LLD of TM) and its anti-inflammatory effects in sepsis. The results indicate an interaction between the LLD of TM and the alarmin HMGB1. We therefore hypothesize that the LLD of TM plays a central role in sepsis-induced cardiac depression by modulating HMGB1 bioavailability.
We hypothesize an increased inflammatory effect in mice lacking the LLD of TM as a result of increased HMGB1 signaling and therefore a reduced survival in mice with polymicrobial sepsis lacking the LLD of TM due to a reduction of anti-inflammatory effects. We expect this signaling cascade to involve the TLR2, TLR4 or RAGE pathway.
The siRNA knockdown of TLR2, TLR4 and RAGE will be used to evaluate respective effects on HMGB1 sequestration after stimulation in cell culture. The cell culture of primary cardiomyocytes was established and the completion of transcriptome-analysis after LPS-stimulation is in process. The establishment of a protocol for transfection of these cells with pcDNA of human full-length TM or pcDNA of human TM lacking the LLD and for knockdown the different receptor pathways via siRNA is ongoing. After stimulation with LPS, we hypothesize that these experiments will indicate a signaling cascade that is involved in the anti-inflammatory effect of the LLD of TM. Furthermore the metabolism of hearts from mice lacking the LLD of TM and wild type controls will be studied after sepsis in the isolated working heart. A murine isolated working heart model with possibilities of measuring glucose and fatty acid oxidation is available for the planned experiments. In future planned experiments, we will use in vivo anti-RAGE, -TLR2 or -TLR4 antibodies and in vivo hydro-dynamic over expression of the LLD of TM to evaluate a possible treatment for sepsis-induced myocardial depression.
Contact
Tel.: +49 (0)3641 - 9 32 31 46
Universitätsklinikum Jena
Klinik für Anästhesiologie und Intensivtherapie
Erlanger-Allee 101
07747 Jena