The food-borne pathogen Campylobacter jejuni responds to the bile salt deoxycholate with countermeasures to reactive oxygen species

Abstract

Bile plays an important role in digestion, absorption of fats, and the excretion of waste products, while concurrently providing a critical barrier against colonization by harmful bacteria. Previous studies have demonstrated that gut pathogens react to bile by adapting their protein synthesis. The ability of pathogens to respond to bile is remarkably complex and still incompletely understood. Here we show that Campylobacter jejuni, a leading bacterial cause of human diarrheal illness worldwide, responds to deoxycholate, a component of bile, by altering global gene transcription in a manner consistent with a strategy to mitigate exposure to reactive oxygen stress. More specifically, continuous growth of C. jejuni in deoxycholate was found to: 1) induce the production of reactive oxygen species (ROS); 2) decrease succinate dehydrogenase activity (complex II of the electron transport chain); 3) increase catalase activity that is involved in H2O2 breakdown; and 4) result in DNA strand breaks. Congruently, the addition of 4-hydroxy-TEMPO (TEMPOL), a superoxide dismutase mimic that reacts with superoxide, rescued the growth of C. jejuni cultured in the presence of deoxycholate. We postulate that continuous exposure of a number of enteric pathogens to deoxycholate stimulates a conserved survival response to this stressor.

Proteome Profiling by Label‐Free Mass Spectrometry Reveals Differentiated Response of Campylobacter jejuni 81–176 to Sublethal Concentrations of Bile Acids

“…It remains to be confirmed whether the bile acid‐induced increase in respiratory chain proteins also leads to higher respiratory activity. However, an increased respiratory chain activity would explain the deoxycholate‐induced higher ROS levels observed by Negretti and coworkers …”

“…Redox enzymes mediating oxidative phosphorylation through the electron carriers are a main source of ROS in bacteria . Twelvefold increased ROS levels as a result of exposure of C. jejuni to 0.05% DOC have been detected directly by measurement of oxidized 2’,7’‐dichlorodihydrofluorescein diacetate fluorescence . In bacteria, the bile acid induced ROS lead finally to toxic DNA damage and induce an increase in catalase activity and a decrease in transcripts for redox enzymes that might contribute to ROS production …”

A porcine ligated loop model reveals new insight into the host immune response againstCampylobacter jejuni

“…Unfortunately, the 12 and 30 hour samples were not able to be evaluated due to an overabundance of eukaryotic RNA. Nevertheless, to help understand the early signals that C. jejuni responds to in the intestinal environment, the data from the pig intestinal loops was compared to C. jejuni cultured in MH broth with 0.05% sodium deoxycholate (DOC, previously published data) 22 and C. jejuni cultured with IPEC-J2 cells (immortalized pig intestinal cells). All comparisons were made against the 'input' samples grown in MH broth to provide consistency and highlight the contributions of the specific condition.…”

“…The supernatant was collected, and the bacteria were recovered by centrifugation and collected in 1/10 volume of ice-cold stop solution (5% phenol, 95% ethanol), flash-frozen in liquid nitrogen, and stored at −80°C until RNA extraction. For IPEC-J2 samples, RNA was processed as described previously 22 . RNA from pig loops was extracted with the SV Total RNA Isolation System (Promega) with 3 mg/mL lysozyme, treated with Turbo DNAse AM1907 (Thermo Fisher), and rRNA was depleted using 1/ 8th reaction volumes of Ribo-Zero Gold rRNA Removal Kit-Epidemiology (Illumina, San Diego, CA) following manufacturer's instructions with ethanol purification.…”

Host Pathogen responses of chicken cells in vitro and in vivo to a diverse population of Campylobacter strains

“…Many chemoattractants for Campylobacter have been found, including some metabolic substrates such as: L-aspartate, L-asparagine, L-cysteine, L-glutamate, pyruvate and Lserine, as well as electron donors and electron acceptors including L-malate, succinate, fumarate, nitrite, and nitrate (Guccione et al, 2008;Mohammed et al, 2004;Velayudhan et al, 2004;Weingarten et al, 2008;Westfall et al, 1986). There are also substances which repel Campylobacter such as bile salts (Beery et al, 1988;Negretti et al, 2017). The sensing of chemoattractants and chemorepellents is mediated by methylaccepting chemotaxis proteins which possess a large cytoplasmic signalling and adaption domain and a periplasmic ligand interaction domain.…”