Escherichia coliO157:H7 gene expression in the presence of catecholamine norepinephrine

Abstract

Various forms of host stresses (e.g. physiological, psychological) are thought to influence susceptibility to pathogenic microorganisms. Catecholamines such as norepinephrine are released into the GI environment during acute stress and may influence the infective process of bacterial pathogens associated with the GI tract. To examine the effects of norepinephrine on expression of virulence factors in Escherichia coli O157:H7, the clinical-type isolate EDL933 (ATCC 43895) was grown in serum-Standard American Petroleum Institute media in the presence or absence of norepinephrine. After 5 h of exposure to norepinephrine, treatment and control cultures (not exposed to norepinephrine) were harvested, their RNA isolated, and gene expression evaluated. There was a dramatic increase in the expression of virulence factor transcripts including stx1, stx2, and eae. Also induced were transcripts involved in iron metabolism. Conversely, there was comparative repression of iron acquisition and phage shock protein-related transcripts in the presence of norepinephrine. Novel observations from these data suggested that exposure to norepinephrine induced glutamate decarboxylase acid resistance as well as an SOS response in E. coli O157:H7. The results corroborate many of the previous findings detailed in the literature and provide new observations that could expand the scope of microbial endocrinology.

Microbial Endocrinology

“…Although variations in the methodologies used for the transcriptional profiling make direct comparisons between the studies difficult, overall the gene expression profiles obtained support the view that exposure to catecholamines enhances expression of genes involved in bacterial pathogenicity (such as motility, iron acquisition, and epithelial cell attachment) [12,17,25,51]. Interestingly, a very recent paper by Peterson et al showed in vitro that stress hormone exposure enhanced the horizontal gene transfer efficiencies of a conjugative plasmid from a clinical host strain of Salmonella Typhimurium to an E. coli recipient [52].…”

“…In an attempt to define the global transcriptional response of bacteria to catecholamine exposure, a number of microarray studies have been undertaken [12,17,25,47]. Although variations in the methodologies used for the transcriptional profiling make direct comparisons between the studies difficult, overall the gene expression profiles obtained support the view that exposure to catecholamines enhances expression of genes involved in bacterial pathogenicity (such as motility, iron acquisition, and epithelial cell attachment) [12,17,25,51].…”

“…Dopamine is produced in a subpopulation of non-sympathetic enteric neurons located within the intestinal wall [8]. Table 1 [ [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] shows the microbes responsive to catecholamine stress hormones. What is most apparent is that the spectrum of hormone responsive microbes is weighted towards bacteria inhabiting the gastrointestinal tract, particularly species such as Escherichia coli, Salmonella, Listeria, Campylobacter, and Yersinia [9, 12,13,[15][16][17][18]22].…”

Evaluation of Major Types of Shiga Toxin 2e-Producing Escherichia coli Bacteria Present in Food, Pigs, and the Environment as Potential Pathogens for Humans

“…Without induction, two-thirds of the strains were identified as poor producers of Stx (0 to 1ϩ), but 99% of the strains were inducible for Stx2e production by mitomycin C. Mitomycin C was chosen as a potent inductor for phage-encoded gene expression in vitro. The inducibility of Stx production is likely to play a role in vivo for pathogenesis, since Stx production was shown to be triggered by neutrophils and norepinephrine in the gastrointestinal tract (13,49). The inducible phenotype could not be related to phage production (data not shown) or to the integrity of the phage P27 genome in these strains.…”

Stress and microbial endocrinology: prospects for ruminant nutrition

“…For instance, Dowd carried out microarray analyses of E. coli O157:H7 virulence gene expression in the presence of NA (Dowd, 2007). He reported that E. coli O157:H7 grown in serum-containing culture medium containing NA showed differential regulation of 101 genes compared with similarly grown non-supplemented controls.…”