A4: Cell type-selective carriers for targeted pharmacological inhibition of Rho-/actin-dependent leukocyte recruitment into the alveolar space after blunt chest trauma
PIs: H. Barth, T. Weil
Blunt chest trauma with resulting lung contusion significantly worsens the outcome of multiply injured patients. The intensity of the lung-contusion-induced inflammation with recruitment of polymorphonuclear neutrophils (PMN) and macrophages (MØ) into the alveolar space is likely to determine the clinical course. Preliminary work from the KFO200 revealed that the enhanced chemotaxis of blood monocytes and interstitial MØ along a chemokine gradient into alveoli and their differentiation into alveolar macrophages (AMØ) with a pro-inflammatory profile substantially contributes to the inflammatory process. Although the precise molecular mechanisms underlying these processes are not completely understood, the targeted pharmacological inhibition of PMN and monocyte/MØ recruitment into the lungs should be beneficial for the outcome of multi-injured patients after blunt chest trauma. Therefore, the aim of this project is the establishment of cell type-selective bacterial protein toxins, which specifically inhibit central regulators of chemotaxis, including Rho-GTPases, F-actin, and the CXC-chemokine receptor 2 (CXCR2). This will allow for more detailed investigation and targeted pharmacological inhibition of PMN and monocytes chemotaxis in vitro, ex vivo, and in a clinically relevant blunt chest trauma animal model.
Since Rho-GTPase activity regulates F-actin dynamics and, hence, CXCR2-mediated signal transduction, both of which are crucial for chemotaxis, the effects of monocyte/MØ-selective Rho-inhibitor C3bot on AMØ recruitment will be investigated in vitro, ex vivo, and in a clinically relevant blunt chest trauma animal model. Moreover, enzymatically inactive C3botE174Q will serve as monocyte/macrophage-selective carrier for targeted delivery of the actin-modifying enzyme C2I into these cells. This will directly inhibit the cells´ actin dynamics thereby preventing chemotaxis. C3botE174Q will also serve for the monocyte/MØ-selective transport of drug delivery platforms such as streptavidin. Such modular transporters will be used for delivery of the enzymatically active domain of pertussis toxin (PT) into the cytosol of peripheral blood monocytes and interstitial MØ to specifically interfere with CXCR2-signalling via PT-sensitive heterotrimeric GTP-binding proteins, e.g. Gi, and thereby inhibit AMØ recruitment into the alveolar space after blunt chest trauma.
For the application of the toxins and transporters into the lung, the recently established biocompatible nanocarriers including biohybrid macromolecules such as albumin hydrogels will be exploited. These molecules show high bioactivity in vivo and are, therefore, expected to enable an efficient delivery and controlled spatio-temporal release of the various inhibitory molecules into the alveolar space. Uptake through the more permeable alveolar epithelial barrier of traumatized animals into the blood will allow to selectively target the blood monocytes. In conclusion, the results will contribute to a better understanding of the role of monocytes for the inflammatory process after polytrauma involving lung contusion and the molecular mechanisms underlying the recruitment of AMØ into the alveolar space, and will likely lead to the development of novel therapeutic strategies to prevent these processes in humans.
Prof. Dr. Holger Barth
Institut für Pharmakologie und Toxikologie
Tel: +49 731 500-65503
Fax: +49 731 500-65502
Prof. Dr. rer. nat. Tanja Weil
Institut für Organische Chemie III
Tel.: +49 731 50 22870
Fax: +49 731 50 22883