Detection of Campylobacter jejuni liver dissemination in experimentally colonized turkey poults

Interactions between gut microbiota and Parkinson's disease: The role of microbiota-derived amino acid metabolism

Non-motor symptoms (NMS) of Parkinson's disease (PD), such as constipation, sleep disorders, and olfactory deficits, may emerge up to 20 years earlier than motor symptoms. A series of evidence indicates that the pathology of PD may occur from the gastrointestinal tract to the brain. Numerous studies support that the gut microbiota communicates with the brain through the immune system, special amino acid metabolism, and the nervous system in PD. Recently, there is growing recognition that the gut microbiota plays a vital role in the modulation of multiple neurochemical pathways via the “gut microbiota-brain axis” (GMBA). Many gut microbiota metabolites, such as fatty acids, amino acids, and bile acids, convey signaling functions as they mediate the crosstalk between gut microbiota and host physiology. Amino acids' abundance and species alteration, including glutamate and tryptophan, may disturb the signaling transmission between nerve cells and disrupt the normal basal ganglia function in PD. Specific amino acids and their receptors are considered new potential targets for ameliorating PD. The present study aimed to systematically summarize all available evidence on the gut microbiota-derived amino acid metabolism alterations associated with PD.

Enrichment and Direct Plating for Detection of Campylobacter in Chicken Liver Rinse and Exudate

ABSTRACT

Foodborne campylobacteriosis has been traced to undercooked chicken liver dishes; thus, it is important to use the best available culture methods when testing for the presence of Campylobacter. We compared two Campylobacter enrichment broths-Bolton formulation and Neogen formulation-in combination with three selective plating media-Campy-Cefex, Campy-Line and RF Campylobacter agars-for detection of Campylobacter from fresh retail chicken livers. In each of three experiments, nine replicate tubs of chicken livers were sampled by drawing exudate and a pooled rinse of five whole liver lobes. Results are reported as number positive and compared by Fisher's exact test. In experiment 1, no combination of enrichment and plating media significantly outperformed another for detection of Campylobacter (P > 0.05); all tubs were found to include Campylobacter in both exudate and liver rinse. In experiment 2, serial dilutions of samples were plated before and after enrichment. Exudate was found to be significantly more likely than rinse to support detection of Campylobacter by direct plating (P < 0.05); most exudate samples included at least 10 CFU Campylobacter per mL. Enrichment improved detection from rinse, but not exudate; all enrichment and plating combinations resulted ≥1,000 CFU/mL from most enriched samples. In experiment 3, samples were diluted before enrichment to determine effect of enrichment on ever lower numbers of Campylobacter. Enrichment did not improve recovery of Campylobacter from exudate or undiluted rinse (P > 0.05). However, when rinse samples were diluted to lower Campylobacter numbers, enrichment improved detection (P < 0.05). Overall, all media combinations tested were equivalent for detection of Campylobacter from chicken livers; sensitivity for detection seemed to be increased by using liver exudate compared with a pooled rinse of liver lobes.

HIGHLIGHTS

Campylobacter jejuni Serine Protease HtrA Induces Paracellular Transmigration of Microbiota across Polarized Intestinal Epithelial Cells

Campylobacter jejuni represents an eminent zoonotic germ responsible for foodborne infections causing campylobacteriosis. In addition, infections with C. jejuni constitute a risk factor for the occurrence of inflammatory bowel disease (IBD). In the latter case, patients show inflammatory reactions not only against C. jejuni, but also against the non-infectious microbiota. However, the involved mechanisms and molecular basis are still largely unclear. We recently reported that C. jejuni breaches the intestinal epithelial barrier by secretion of serine protease HtrA (high temperature requirement A), which cleaves several major tight and adherens junction proteins. In the present study, we aimed to study if HtrA-expressing C. jejuni may also trigger the transepithelial migration of non-pathogenic gastrointestinal microbiota. Using confocal immunofluorescence and scanning electron microscopy, we demonstrate that C. jejuni wild-type (wt) as well as the isogenic ∆htrA mutant bind to the surface of polarized intestinal Caco-2 epithelial cells, but do not invade them at the apical side. Instead, C. jejuni wt, but not ∆htrA mutant, disrupt the cellular junctions and transmigrate using the paracellular route between neighboring cells. Using transwell filter systems, we then co-incubated the cells with C. jejuni and non-invasive microbiota strains, either Escherichia coli or Lactococcus lactis. Interestingly, C. jejuni wt, but not ∆htrA mutant, induced the efficient transmigration of these microbiota bacteria into the basal compartment. Thus, infection of the intestinal epithelium with C. jejuni causes local opening of cellular junctions and paracellular translocation in an HtrA-dependent manner, which paves the way for transmigration of microbiota that is otherwise non-invasive. Taken together, these findings may have impacts on various Campylobacter-associated diseases such as IBD, which are discussed here.