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Stranded mRNA sequencing of chicken cecal tissue

ABSTRACT: The objective of this study was to determine if Salmonella colonization of chickens could be reduced through competitive exclusion using a defined community of chicken commensal bacteria. One-day old White Leghorn chicks, hatched on-site, were randomly divided into experimental groups and given an oral gavage of either a defined community of 15 bacterial species (DC), cecal contents (CC), or sterile PBS (control; CT). After one week, birds were euthanized for cecal content collection (pre-Salmonella sample) while the remaining birds were orally gavaged 1 X 10^8 colony forming units (CFU) of Salmonella enterica ser. Heidelberg strain 2813 (SH2813). Bacterial counts for three post-Salmonella timepoints (3, 14, and 28 days post inoculation; dpi) were evaluated. Bacteriological enumeration was performed by plating cecal contents onto Salmonella selective agar to determine CFU/g in each group for all collection days. Cecal contents were also used for 16S amplicon sequencing. Cecal tissue was used for stranded mRNA sequencing (RNA-Seq).

ORGANISM(S): Gallus gallus

PROVIDER: GSE286977 | GEO | 2026/01/30

REPOSITORIES: GEO

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Project description:Consumption of contaminated poultry products is one of the main sources of human campylobacteriosis, of which Campylobacter jejuni subsp. jejuni (C. jejuni) and C. coli are responsible for approximately 98% of the cases. The ceca of commercial turkeys are the main anatomical site where Campylobacter asymptomatically colonizes. We have previously colonized the ceca of commercial turkey poults with C. jejuni, and demonstrated acute changes in cytokine gene expression in cecal tissue and histologically scored intestinal lesions at 2 days post-inoculation (dpi). The host-response of turkeys to C. coli colonization is unknown. Cecal tonsils (CT) are an important part of the gastrointestinal-associated lymphoid tissue that function to sample material passing in and out of the ceca and generating immune responses against intestinal pathogens. The CT immune response towards Campylobacter is unknown. In this study, we generated a C. coli kanamycin-resistant construct (CcK) for enumeration from cecal contents after experimental challenge. In vitro analysis of CcK demonstrated no changes in motility when compared to the parent isolate, but in vitro growth rates were significantly different than the parent strain. Poults were inoculated by oral gavage with CcK (5x10^7 cfu) or sterile-media (mock-colonized), and euthanized at 1 and 3 dpi. At both time points, CcK was recovered from cecal contents, but not from the mock-colonized group. As a marker of acute inflammation, serum alpha-1 acid glycoprotein was significantly elevated at 3 dpi in CcK inoculated poults compared to mock-infected samples. Significant histological lesions were detected in cecal and CT tissues of CcK colonized poults at 1 and 3 dpi, respectively. RNAseq analysis identified 250 differentially expressed genes (DEG) in CT from CcK colonized poults at 3 dpi, of which 194 were upregulated and 56 were downregulated. From the DEG, 9 significantly enriched biological pathways were identified, including platelet aggregation, response to oxidative stress and negative regulation of oxidative stress-induced intrinsic apoptotic signaling pathway. These data suggest that C. coli induced an acute inflammatory response in the intestinal tract of poults, and that platelet aggregation and oxidative stress in the CT may affect the turkey’s ability to resist Campylobacter colonization. Results from this study provide insight into host-response of the turkey CT to Campylobacter colonization. These findings will help to develop and test Campylobacter mitigation strategies to promote food safety in commercial turkeys.

Project description:Background: Inflammatory bowel diseases (IBD) may be caused in part by aberrant immune responses to commensal intestinal microbes including Bacteroides thetaiotaomicron (B.theta). Healthy, germ-free HLA-B27 transgenic (Tg) rats develop chronic colitis when colonized with complex gut commensal bacteria whereas non-transgenic (nTg) rats remain disease-free. However, the role of B.theta, a well-characterized anaerobic commensal bacterium, in causing disease in Tg rats is unknown nor is much known about how microbes respond to host inflammation. Methods: Tg and nTg rats were monoassociated with a human isolate of B.theta. Colonic inflammation was quantified by blinded histological scoring and real-time RT-PCR assays of pro-inflammatory cytokines. Cecal bacterial concentrations were measured by quantitative plating. Whole genome transcriptional profiling of B.theta recovered from ceca was performed using custom GeneChips and data analyzed using dChip, Significance Analysis of Microarrays, and Gene Set Enrichment Analysis (GSEA) software. Results: B.theta monoassociated Tg rats had significantly more colonic inflammation and increased colonic levels of pro-inflammatory cytokine mRNAs compared to nTg controls. Transcriptional profiles of cecal B.theta were significantly different in Tg vs. nTg rats. GSEA revealed that the Gene Ontology molecular function of receptor activity, which is comprised mainly of genes that encode nutrient binding proteins, was significantly enriched with genes upregulated in B.theta from Tg rats. KEGG canonical pathways of ribosome, oxidative phosphorylation, pyrimidine metabolism, purine metabolism, peptidoglycan biosynthesis, and metabolism were significantly enriched with genes downregulated in B.theta from Tg rats. Numbers of viable bacteria/gram cecal contents in Tg vs. nTg rats were not significantly different. Conclusions: B.theta induces mild colitis in HLA-B27 Tg rats, which is associated with changes in the expression of microbial metabolic and nutrient binding pathways, but no difference in concentrations of luminal bacteria. Mechanistic studies of differentially expressed B.theta genes may reveal novel pathways that contribute to IBD. The fully-sequenced human fecal isolate of B.theta (VPI-5482) was grown on Brain-Heart Infusion (BHI) agar and in BHI broth under strict anaerobic conditions using pre-reduced media. Adult germ-free HLA-B27/b2 microglobulin transgenic rats and adult germ-free non-transgenic littermate were monoassociated with B.theta for six weeks in gnotobiotic isolators at the National Gnotobiotic Rodent Resource Center at UNC Chapel Hill. Bacterial RNA was isolated from rat cecal contents and hybridized on Affymetrix human gut microbiota community GeneChip.

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Stranded mRNA sequencing of chicken cecal tissue

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