Alam Project

University Of Kentucky, Lexington KY

Investigators

Linked publications & trials

Abstract

PROJECT SUMMARY – PROJECT 7 (ALAM) Campylobacter jejuni is the primary pathogen responsible for bacterial gastrointestinal infections worldwide and is the leading cause of enteric inflammation in the United States, which can further lead to late-onset diseases such as Guillain Barré Syndrome, colorectal cancers, IBD, and IBS. Importantly, C. jejuni has been designated as a serious antibiotic resistance threat by both WHO and CDC. The numerically vast and taxonomically diverse gut microbial communities affect the health and bacterial infection in the intestine. We and others have shown that the intestinal bloom of dysbiotic E. coli is strongly associated with exacerbated C. jejuni infection. However, there is a critical knowledge gap in developing potential agents that target only specific pathogens without disturbing the entire gut microbiota. This proposal’s objective is to elucidate the chemical biology of microbial metabolites and small molecules selective against intestinal C. jejuni and E. coli pathogens that cause intestinal infection and inflammation. Our exciting preliminary met’omics analysis identified increased abundances of E. coli’s lysine decarboxylase (CadA) system during C. jejuni infection in mice. The CadA enzyme catabolizes lysine to polyamine cadaverine but C. jejuni fails to synthesize cadaverine. Interestingly, the dysbiotic E. coli, through its CadA enzyme and metabolite cadaverine, promote C. jejuni infection by augmenting chemotaxis, motility, antibiotic susceptibility, and toxin production. We also found that cadaverine activates C. jejuni’s transducer-like protein, Tlp3. A C. jejuni Δtlp3 mutant displayed attenuated chemotaxis and virulence, indicating Tlp3 as a potential anti-virulent target. Through a combined CTCB Bio Core CadA virtual and wet-bench screen we identified 6-aminohexanoate as a prototype CadA inhibitor. Our central hypothesis is that the cadaverine- producing CadA enzyme and cadaverine-sensing chemoreceptor Tlp3 are druggable targets to eliminate E. coli and C. jejuni by inhibiting chemotaxis, survival, and virulence during intestinal infection. Aim 1 will investigate the inhibitory impact and efficacy of top-ranked hit compounds on CadA in cadaverine production, bacterial growth, and C. jejuni pathogenesis. In Aim 2, we will virtually and experimentally screen small molecules that inhibit C. jejuni’s chemotactic receptor Tlp3. Finally, in Aim 3, we will assess the combined impact of CadA and Tlp3 inhibitors on C. jejuni-mediated infection in the mouse model. This project is both conceptually and technically innovative in developing a selective ‘anti-virulent’ agent for C. jejuni. Integrated CTCB core support and mentorship will facilitate this project in a number of key ways. Specifically, the CTCB Bio Core will support CadA and Tlp3 virtual and wet-bench screening (Aims 1 and 2) and simple antibacterial and eukaryotic toxicity assessments for hits, while the Chem Core will support de novo CadA and Tlp3 ligand design and ligand optimization chemistries (Aims 1 and 2) and preformulation and stability studies in the context of proposed animal studies (Aim 3). This will be augmented by a CTCB mentorship team with extensive expertise in polyamine biosynthesis and signaling, gut microbiome, pharmaceutical science, and antibiotic drug development.