Metabolomic profiling of Burkholderia thailandensis infection of airway epithelial cells provides insights into potential therapeutic targets.

Burkholderia pseudomallei, a gram-negative saprophyte that causes melioidosis, has been classified as a potential bioweapon, posing a serious global threat. Metabolic re-wiring, production of virulence effectors, evasion/suppression of host defenses, and modification of host cell functions constitute important mechanisms in the pathogenesis of infection. Elucidating the metabolism during intracellular growth of the pathogen is critical for learning the mechanisms by which infection is accomplished. Currently, the metabolic activities associated with, and potentially mediating, host-pathogen interactions during infection are not well understood, but recent advances in untargeted mass spectrometry-based metabolomics methods are enabling the narrowing of this knowledge gap. Here, we used untargeted metabolomics analysis to identify polar metabolites produced by Burkholderia thailandensis E264 (a surrogate for B. pseudomallei) and airway epithelial cells (the murine cell line LA-4) during the intracellular stage of infection. Pathway analysis of annotated metabolites that differed in abundance in mock-challenged versus B. thailandensis-challenged host cells revealed changes in the activity of a diverse set of metabolic pathways that could be targeted to combat Burkholderia infections. These include pathways that mediate metabolic processes occurring in both the pathogen and host (e.g., polyamine biosynthesis, NAD+ [nicotinamide adenine dinucleotide] metabolism, and the citric acid cycle), as well as several pathogen-specific pathways (peptidoglycan biosynthesis, ornithine lipid production, and quorum sensing-regulated secondary metabolites). The observed shift in the metabolome shows commonalities with other gram-negative pathogens during infection. Our results provide insight into the changes in metabolism associated with Burkholderia infection and reveal several promising targets for therapeutic interventions.IMPORTANCEBurkholderia pseudomallei is the causative agent of infectious disease, namely melioidosis. When inhaled, Burkholderia pseudomallei causes severe respiratory infections. Due to the potential for severe airborne infections, it is classified as a Tier 1 biothreat agent. The intrinsic antibiotic resistance and increased global prevalence necessitate the development of alternative treatments. Infection triggers a metabolic "arms race" between host and pathogen, where both organisms dramatically alter their metabolism to outcompete one another. By studying these changes, one can identify new therapeutic targets for drug discovery and better understand the mechanisms pathogens use to establish and maintain infection. We performed an untargeted metabolomics analysis of murine epithelial cells co-cultured with Burkholderia thailandensis, a surrogate for Burkholderia pseudomallei, to identify the metabolic shifts that occur during intracellular infection. Using these analyses, we propose several pathways and therapeutic interventions to enable pathogen clearance.