Molecular profiling: Catecholamine modulation of gene expression in enteropathogenic bacteria

Abstract

Investigations of the enteric pathogens Escherichia coli O157:H7, Salmonella enterica serovar Typhimurium, and Vibrio parahaemolyticus have demonstrated that these bacteria can respond to the presence of catecholamines including norepinephrine and/or epinephrine in their environment by modulating gene expression and exhibiting various phenotypes. For example, one of the most extensively investigated phenotypes following exposure of E. coli and S. Typhimurium to norepinephrine is enhanced bacterial growth in a serum-based medium. Norepinephrine-enhanced bacterial growth is due, in part, to increased iron availability, and transcriptional profiling indicates differential expression of genes encoding iron acquisition and transport proteins. The motility of E. coli and S. Typhimurium is also enhanced in the presence of norepinephrine or epinephrine and increased flagellar gene expression has been described. In E. coli O157:H7, norepinephrine exposure increases expression of the genes encoding Shiga toxin and operons within the locus of enterocyte effacement (LEE). For V. parahaemolyticus, norepinephrine stimulates cytotoxic activity against Caco-2 cells by increasing the transcription of type III secretion system 1 genes. Alterations in the transcriptional response of enteric bacteria to catecholamine exposure in vivo may enhance bacterial colonization and pathogen virulence. This chapter will review the current literature on the transcriptional response of these enteropathogens to catecholamines.