Effects of dietary yeast cell wall supplementation on growth performance, intestinal Campylobacter jejuni colonization, innate immune response, villus height, crypt depth, and slaughter characteristics of broiler chickens inoculated with Campylobacter jejuni at d 21

Intestinal Colonization of Campylobacter jejuni and Its Hepatic Dissemination Are Associated with Local and Systemic Immune Responses in Broiler Chickens

“…The absence of Th17 signaling at 7 dpi might compromise the integrity of the intestinal epithelial barrier, which could, in turn, facilitate the reduced expression of tight junction proteins in the presence of C. jejuni (as we previously reported [37]) and the ensuing hepatic spread. Furthermore, the significant increase in IL-10 expression in the cecal tonsils of C. jejuniinoculated birds is in accordance with the literature [14,16,22] and would result in the long-term colonization of C. jejuni in the intestine and the lack of observed pathologies [12].…”

“…C. jejuni lipooligosaccharide (LOS), lipopeptides, and unmethylated cytosine–phosphate–guanine nucleotide DNA motifs are recognized by the chicken’s TLR4, TLR2, and TLR21, respectively [ 9 ]. This recognition induces an innate immune response in broiler chickens characterized by the increased expression of various pro-inflammatory chemokine and cytokine-encoding genes in the ileal and cecal tissues ( CXCLi2 , IL-6 , and IL-1β ) [ 11 , 12 , 13 , 14 , 15 , 16 ], by a modulation of the host defense peptide gene expression in the intestinal tissues [ 17 , 18 , 19 ], and by an increase in the expression of the inducible nitric oxide synthase ( iNOS )-encoding gene in cecal tissue [ 20 ]. Furthermore, this early immune response leads to the infiltration of heterophils in ileal and cecal tissues [ 11 ].…”

“…Th17 cells are abundant in the intestinal lamina propria; they prevent the entry of pathogenic bacteria and maintain the integrity of the intestinal barrier by secreting pro-inflammatory cytokines, including IL-17A, IL-17F, and IL-22 [ 21 ]. An anti-inflammatory response has also been observed in avian cecal tissues, induced by the expression of IL-10 [ 12 , 13 , 16 , 22 ], a key regulatory cytokine designed to restrain inflammation and ensure immune homeostasis. Lack of IL-10 expression may cause mucosal damage and diarrhea in Campylobacter -colonized chickens [ 12 ].…”

Characterizing the Effect of Campylobacter jejuni Challenge on Growth Performance, Cecal Microbiota, and Cecal Short-Chain Fatty Acid Concentrations in Broilers

“…The C. jejuni challenge did not affect the performance production, feed intake, and feed conversion ratio (Table 2) compared to the control group (p > 0.05). These findings agree with results reported in different studies, as the C. jejuni challenge on day 14 [13] or day 21 [18] did not alter the performance parameters compared to the control group (p > 0.05). Such results highlight the near-commensal nature of C. jejuni and its relatively harmless infection, whose effects are typically limited to the gut.…”

“…The difference in structure and avian mucus efficacy in trapping pathogens is a major reason behind the benign infection in broilers [16,17]. Additionally, different reports emphasized the commensal nature of C. jejuni infection in broilers, highlighting the absence of an effective immune response despite the high colonization rate in the ceca [13,18]. Nonetheless, other papers have challenged the notion of C. jejuni being merely a commensal bacterium, citing observed reduction in performance parameters following the infection of C. jejuni [19][20][21][22].…”