Campylobacter jejuni stimulates a robust cytokine response in the cecal tonsil following a repeated challenge infection model

Campylobacter spp., and especially C. jejuni, are leading causes of bacterial-derived foodborne illness in humans. Poultry are known reservoirs, and in many instances, Campylobacter are thought to be commensal organisms harmlessly residing in the gastrointestinal tract of poultry; therefore, human illness could result from mishandling or consuming raw or undercooked chicken products contaminated with Campylobacter. The objective of this study was to prime the chickens with a low dose of C. jejuni at a young age followed by a higher dose later and monitor changes to key inflammatory and regulatory cytokines and chemokines. Broiler chicks (2-days-of-age) were administered 1 × 10³ colony forming units (cfu)/mL C. jejuni, (0.5 mL, orally) followed by a second dosage of 1 × 10⁷ cfu/mL (1 mL, orally) at 28-d-of-age. At 35-d-of-age, the chickens were necropsied and the cecal tonsil was collected. The study was conducted twice. Cytokine (IL1β, IL6, IL10, IFNγ, TGFβ4) and chemokine (CXCL8) mRNA expression was measured in the cecal tonsil. Expression of IL1β, IL10, TGFβ4, and CXCL8 mRNA were significantly higher (2.6 - 5.8-fold; P ≤ 0.04) in the cecal tonsils of the chickens subjected to the two doses of C. jejuni. The C. jejuni challenges had no effect on the mRNA expression levels of IL6 and IFNγ (P > 0.05). These data indicate repeated exposure to C. jejuni stimulates a diverse and robust cytokine response in important lymphoid tissue indicating the host recognizes the C. jejuni as pathogenic and mounts a response yet a persistent infection is still established.