Rational Development of Small Molecules Targeting Virulence of Pseudomonas aeruginosa

Pseudomonas aeruginosa is the leading cause of nosocomial infection in the UK and recognised as a critical priority pathogen in need of new antibiotics by the World Health Organisation. Its large genome allows it to adapt to a vast range of ecological niches meaning it is found almost ubiquitously in the environment, but as an opportunistic pathogen it poses almost no threat unless an individual is immunocompromised. P. aeruginosa causes a myriad of infections to burn, cancer, ventilated, and AIDS patients amongst many others. However, it is most associated with cystic fibrosis sufferers, colonising the lungs on average by 1yr of age and progressing to be the dominant infectious pathogen in the lungs for life. It is the leading cause of mortality in CF patients with ~80% dying from P. aeruginosa related lung failure. P. aeruginosa is a multi-drug resistant pathogen with many intrinsic and acquired forms of resistance that can result in a cycle of infection, inflammation, tissue damage and scarring that ultimately results in lung failure. Without the development of any new commercial antibiotics for over 30 years focuses have shifted in the scientific literature to identifying new approaches to tackle infectious diseases. Targeting virulence factors poses many potential benefits, such as lower selection pressure driven resistance, shorter treatment times when used in conjunction with antibiotics, and preservation of gut microbiota to list just a few. P. aeruginosa has a large arsenal of virulence factors it uses to cause infections and the two major factors studied in this project are the type III secretion system and swarming motility. During this project rational in silico drug discovery methods were used to identify small molecule inhibitors of ExsA, the master transcriptional regulator of the type III secretion system. The molecules were ordered from the Enamine and the NCI Diversity Set V libraries. Some small molecules were identified that bound to, but did not prevent activity of ExsA, and others that protected A549 lung epithelial cells in vitro from P. aeruginosa mediated cytotoxicity, but not by inhibition of ExsA. Upon further investigation it was found that phenyl piperazine molecules improved survival in vivo of Galleria mellonella in acute infection models by inhibiting the swarming activity of P. aeruginosa. How or if there is a link between the selection of compounds to inhibit ExsA and the inhibition of swarming is unknown, however the work in this project shows that phenyl piperazine molecules inhibit the expression of flagella under swarming conditions most likely by targeting a Class III or IV regulator in the swarming regulatory hierarchy. This chemical class has therapeutic potential to be used as an anti-virulence treatment against P. aeruginosa infections and a full chemical assessment of the scaffold should be completed to move forward with patenting these compounds.

Name dc:type.qualificationname

Doctor of Philosophy (PhD)

Level dc:type.qualificationlevel

Doctoral

Grantor dc:publisher.institution

University of Cambridge

Year dc:date.issued

2021

Author dc:creator

• Triniman, Rory

Advisor dc:contributor.advisor

• Rahman, Taufiq

• Pseudomonas aeruginosa
• drug discovery
• type III secretion system
• swarming
• flagella
• ChpD

Licence

• https://www.repository.cam.ac.uk/bitstreams/4401bac6-9cf0-4ff9-920b-4ea94aa7b47d/download
• https://www.rioxx.net/licenses/all-rights-reserved/

Language dc:language

eng

DOI dc:identifier.doi

https://doi.org/10.17863/CAM.70635

OAI identifier oai:identifier

oai:www.repository.cam.ac.uk:1810/323181