Characterisation of the efficacy of two novel host-directed therapies, SCD-19 and 4-octyl itaconate, for the treatment of Pseudomonas aeruginosa infection in cystic fibrosis.
Citation:
O'NEILL, ANDREW, Characterisation of the efficacy of two novel host-directed therapies, SCD-19 and 4-octyl itaconate, for the treatment of Pseudomonas aeruginosa infection in cystic fibrosis., Trinity College Dublin.School of Medicine, 2021Abstract:
Cystic Fibrosis (CF) is a life limiting genetic disease, which is caused by genetic mutations which result in defective function of the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR). In CF, patients experience frequent hospitalisations from a young age as a result of recurrent respiratory infections and inflammatory lung damage, with CF patients having a median life expectancy of only 31 years. Therefore, currently there is an urgent unmet clinical need for the development of novel anti-inflammatory and antibacterial therapies in the treatment of CF.
Within the CF lung, the build-up of thick mucus secretions provides a microenvironment which is conducive to bacterial colonisation and inflammation. Pseudomonas aeruginosa (P. aeruginosa) is the most commonly isolated pathogen from the CF lung. CF patients develop a series of recurrent, intermittent colonisations of P. aeruginosa before the acquisition of a biofilm-driven chronic infection. The establishment of a chronic infection drives high levels of respiratory inflammation and consequent irreversible lung damage. Furthermore, these chronic infections develop a myriad of antibiotic resistant characteristics; with multidrug-resistant infections becoming a major problem in CF. Anti-microbial resistance is one of the biggest challenges facing society as a whole, with estimations that up to 10,000,000 people a year will die due to antibiotic resistant infections. As such, there is a specific unmet clinical need for the development of novel therapies that target P. aeruginosa-induced inflammation, biofilm formation and infection in CF patients.
The Donnelly Lab has previously demonstrated a role for macrophage migration inhibitory factor (MIF) in the pathogenesis of CF. CF patients expressing high levels of MIF have a more rapid decline in lung function, earlier P. aeruginosa colonisation compared with CF patients with low MIF expression levels. Furthermore, our group has previously demonstrated that MIF promotes P. aeruginosa biofilm formation through upregulation of genes involved in bacterial quorum sensing, alginate expression and mucoid conversion. Previously, The Donnelly Lab have described the successful use of a novel, small molecular weight inhibitor of MIF tautomerase activity, SCD-19, both in vitro and in vivo using in a murine model of chronic P. aeruginosa infection. In this model, SCD-19 promoted bacterial clearance and limited respiratory inflammation.
Here, we examined the role of MIF in P. aeruginosa biofilm formation on airway epithelial cell monolayers. Furthermore, we investigated the efficacy of SCD-19 loaded nanoparticles in the modulation of heat killed P. aeruginosa (HKPA) induced macrophage responses and MIF driven P. aeruginosa biofilm formation. We demonstrated a role for MIF in P. aeruginosa biofilm formation on airway epithelial cell monolayers. We also showed that SCD-19 and SCD-19 loaded nanoparticles modulate this process. Furthermore, we also illustrated that SCD-19 and SCD-19 loaded nanoparticles modulate HKPA-induced TNF-α and RANTES protein production in macrophages. We also detailed, for the first time, the characterisation of bone marrow derived macrophages (BMDMs) from novel, humanised mice which possess a 5-CATT or 7-CATT repeat in the promoter region of their MIF gene.
In this thesis, we also examined the effects of itaconate and 4-octyl itaconate (4-OI) in the context of P. aeruginosa infection. Itaconate is a well-established immunomodulatory by-product of the tricarboxylic acid (TCA) cycle which displays known antibiotic properties. 4-OI is a cell permeable itaconate derivative which is used in cellular experiments as there are limited reports of an itaconate receptor or transporter. We proposed that 4-OI and itaconate treatment would be beneficial in the context of P. aeruginosa inflammation. Here, we demonstrated that 4-OI limited P. aeruginosa-mediated inflammatory responses of BMDMs, promoted the expression of protective antioxidant factors and enhanced BMDM-mediated P. aeruginosa killing. We also demonstrated that itaconate possesses potent antipseudomonal properties, limiting P. aeruginosa growth, biofilm formation and pyocyanin production. Furthermore, we demonstrated that both 4-OI and itaconate, respectively, promoted survival in vivo in a Galleria mellonella model of P. aeruginosa infection.
In conclusion, the results from this study suggest that SCD-19 and 4-OI, respectively, may represent two novel host-directed therapies for the treatment on P. aeruginosa infection in cystic fibrosis.
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Science Foundation Ireland (SFI)
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https://tcdlocalportal.tcd.ie/pls/EnterApex/f?p=800:71:0::::P71_USERNAME:ONEILA20Description:
APPROVED
Author: O'NEILL, ANDREW
Advisor:
Donnelly, SeamasPublisher:
Trinity College Dublin. School of Medicine. Discipline of Clinical MedicineType of material:
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