Oral Treatments With Probiotics and Live Salmonella Vaccine Induce Unique Changes in Gut Neurochemicals and Microbiome in Chickens

Abstract

Cross-talk between the gut microbiota and neurochemicals affects health and wellbeing of animals. However, little is known about this interaction in chickens despite their importance in food production. Probiotics and live Salmonella vaccines are microbial products commonly given orally to layer pullets to improve health and ensure food safety. This study's objective was to determine how these oral treatments, individually or in combination, would impact the gut environment of chickens. White Leghorn chicks were either non-treated (CON) or orally given probiotics (PRO), a recombinant attenuated Salmonella vaccine (RASV; VAX), or both (P+V). Birds were fed with probiotics daily beginning at 1-day-old and orally immunized with RASV at 4-days-old and boosted 2 weeks post-primary vaccination. At 5 weeks, ceca content, ceca tissues, and small intestinal scrapings (SISs) were collected from ten birds/group post-euthanasia for analyses. Catecholamine, but not serotonergic, metabolism was affected by treatments. Dopamine metabolism, indicated by L-DOPA and DOPAC levels, were increased in P+V birds versus CON and PRO birds. Based on 16S sequencing, beta diversity was more similar among vaccinated birds versus birds given probiotics, suggesting live Salmonella vaccination has a major selective pressure on microbial diversity. Abundances of Akkermansia muciniphila and Enterobacteriaceae positively correlated with levels of tyrosine and norepinephrine, respectively. Both enumeration and 16S sequencing, determined that PRO exhibited the greatest levels of Enterobacteriaceae in the ceca and feces, which was associated with greater IgA production against E. coli virulence factors as tested by ELISA. In summary, we demonstrate that using probiotics alone versus in combination with a live vaccine has major implications in catecholamine production and the microbiota of layer pullets. Additionally, unique correlations between changes in some neurochemicals and specific bacteria have been shown.

Japanese quail (Coturnix japonica) as a novel model to study the relationship between the avian microbiome and microbial endocrinology-based host-microbe interactions

“…This is immediately important to poultry because norepinephrine was demonstrated to enhance virulence and growth of the human foodborne pathogen Campylobacter jejuni in vitro [ 19 ] as well as to increase gastrointestinal colonization of C. jejuni in chickens in vivo [ 13 ]. Although C. jejuni colonization occurs to a greater extent in the cecal mucosal crypts with lesser colonization along the small intestine [ 20 ], little is known [ 12 ] about the concentrations of norepinephrine in different regions of the avian gut or whether norepinephrine levels exhibit plasticity in response to stress, and if this may help explain C. jejuni colonization patterns. While the cecum is therefore of particular relevance in mechanisms of neurochemical-mediated avian host-pathogen interaction, in rodents, bacterial colonization and infection of the cecum have been demonstrated to rapidly affect brainstem function and host behavior, underscoring the relevance of the cecal microbiome outside of the gastrointestinal tract [ 21 , 22 ].…”

Evaluation of Live Bacterial Prophylactics to Decrease IncF Plasmid Transfer and Association With Intestinal Small RNAs

“…In conclusion, our findings suggest the combination of these live prophylactics, despite not being specifically designed to target AMR and virulence plasmids, reduced abundances of IncF virulence plasmids and associated ExPEC characteristics in fecal E. coli , by potentially reducing intestinal smRNA levels. This suggests that combining these probiotics and live vaccines may reduce antimicrobial resistance by reducing IncF plasmid transfer between intestinal E. coli as well as directly antagonizing Enterobacteriaceae colonization and infection ( Redweik et al, 2019 , 2020 ). However, it should be noted that these samples were taken within a specific time window pre-lay and that these pullets were from the same flock.…”

“…Samples in this study were taken from chickens used in previous studies ( Redweik et al, 2019 , 2020 ). Briefly, 1-day-old specific pathogen-free White Leghorns (straight run mix of males and females; VALO Biomedia, Adel, IA) fed Purina ® Organic Starter-Grower were either orally vaccinated with an RASV alone (VAX), supplemented with a commercial probiotic supplement ( Bacillus subtilis , Lactobacillus acidophilus , Pediococcus acidilactici , Pediococcus pentosaceus , Saccharomyces pastorianus ) alone (PRO), or treated with both (P + V).…”

“…In addition to bacterial pathogens, non-pathogenic bacteria like probiotics ( Chen et al, 2017 ) can affect chicken intestinal smRNA levels. Previously, we found that immunization with a live Salmonella vaccine reduced Enterobacteriaceae in the ceca and feces, regardless of probiotic supplementation ( Redweik et al, 2019 ). The aim of this study was to determine whether live prophylactics affect the level of E. coli carrying plasmids and genes encoding AMR and ExPEC virulence factors in the chicken intestine as well as whether this effect is correlated with smRNAs.…”

Serotonin modulates Campylobacter jejuni physiology and in vitro interaction with the gut epithelium

“…Previous studies have identified serotonin concentrations in full thickness sections of the intestinal tract of various chicken breeds ( Phillips et al., 1961 ; Beaver and Wostmann, 1962 ; Rawdon, 1984 ). However, a literature search (PubMed, key terms used “chicken,” “serotonin,” “lumen,” “content,” “gut,” and/or “intestine”) revealed only a single study ( Redweik et al., 2019 ) to have determined serotonin concentrations in the luminal content of any gut region. Considering evidence in rodents reporting serotonin concentrations to differ according tissue type ( Thompson, 1966 ), further investigation into the biogeography of serotonin distribution in the chicken intestinal tract is warranted.…”