Investigating non-tuberculosis mycobacteria serine-threonine kinases as targets for antibiotic resistance attenuation

Pulmonary disease caused by non-tuberculous mycobacteria (NTM-PD) is becoming increasingly recognised worldwide. These infections are often chronic in nature, requiring combinations of 3+ antibiotics for treatment. However, such complex multidrug regimens are poorly host-tolerated and due to intrinsic resistance to most antibiotics, poor eradication rates are observed for NTM-PD. Furthermore, the efficacy of beta-lactams for the treatment of NTM-PD is limited as these bacteria produce beta-lactamases. However, recent research has demonstrated that using beta-lactamase inhibitors (BLIs) in combination with beta-lactams improves susceptibility to these antibiotics. Moreover, NTM appear to have the same serine/threonine kinase (STK) signalling system and 3-3 peptidoglycan crosslinking pattern as enterococci, likely also contributing to beta-lactam resistance.
We hypothesise that the STKs in NTM could be rendered inactive using repurposed kinase inhibitors and combined with well host tolerated beta-lactams that are currently not used for NTM therapy. If combined with BLIs into a suitable inhalation formulation therapy, this could be a powerful therapeutic pathway for difficult-to-treat NTM-PD.
In this project, we will clone and purify STKs from selected NTM strains, starting with Mycobacterium abscessus. We intend to explore the binding and inhibition of the STKs using known kinase inhibitors, as well as by creating genetic knockouts of these essential mycobacterial kinases. Additionally, we will test combinations of kinase inhibitors and beta-lactams in checkerboard assays to assess for synergistic activity. These drug combinations will be further validated ex vivo using a pig lung model developed by the Harrison lab, which uses bespoke culture media and conditions that better represent the lungs of NTM-PD patients. It is hoped that this work will help us to better understand antibiotic resistance in NTM and form the basis for improving the treatment of NTM-PD.