Design, synthesis and lead generation of novel siderophore conjugates for the detection and treatment of infections by Gram-negative pathogens
Therapeutics
- Mark Brönstrup, Helmholtz Centre for Infection Research, Germany (Coordinator)
- Doron Shabat, Tel-Aviv University, Israel (Partner)
- Isabelle Schalk, CNRS, Université de Strasbourg, France (Partner)
Infections caused by multidrug-resistant Gram-negative bacteria result in significant mortality and morbidity worldwide. In line with this, all pathogens that received a ‘critical’ status by the recently established WHO priority list were drug-resistant Gram-negative species. The reasons for limited success of pharmaceutical research programs in the area of antibiotics have been carefully analyzed: the main hurdle is the limited understanding how to get drugs into Gram-negative bacteria. Thus, there is a strong need for novel, innovative drugs against infections caused by Gram-negative pathogens. There is also a lack of tools to diagnose bacterial infections at deep body sites, e.g. on implant surfaces. In the project SCAN (Siderophore Conjugates Against gram-Negatives), we apply a rational design approach to establish a targeting conjugate platform that can be used to both diagnose and treat bacterial infections (‘theranostics’ principle). The conjugates are actively transported into bacteria through their iron transport machinery that accepts siderophores as substrates. As this resembles the strategy of ancient Trojan warriors, the approach has been named the ‘Trojan Horse Strategy’. This concept has recently been validated clinically, a first drug (Fetroja) has been approved and is available to patients. We will design and synthesize artificial siderophores that employ novel central scaffolds and combinations of iron-binding motifs. Those will be coupled with hitherto unexplored effectors: RNA polymerase inhibitors are employed as potent antibiotics, and chemiluminescent probes will be used for imaging. As a linkage between siderophore and antibiotic, cleavable, self-immolative linkers will be constructed. The conjugates will be characterized in cellular assays and in animal infection models. Their translocation and resistance mechanisms will be investigated by genetic and proteomic methods. The project should yield novel antibiotic lead structures as well as activatable bacterial probes with proven efficacy in vivo to detect and treat infections. Taken together, the afforded antimicrobials and moreover the novel theranostics could be tools that allow for strain-specific, potent treatment and monitoring of bacterial infections, addressing a major medical need expressed by the WHO.
