Rhythmatic immune response to Campylobacter jejuni inoculation revealed by immune factors level in serum.

1. This study examined the rhythmatic immune response of chickens in the early stages of Campylabacter jejuni infection over time. Chickens were inoculated with C. jejuni at 10:00, 14:00 and 18:00 h, respectively.2. The C. jejuni populations in the caecal and the levels of IL-8, IL-18, IL-1β, IgA, IgY and cytokine signal transduction inhibitor 3 protein (SOCS3) in serum for each individual were measured at different hours after inoculation (hpi). Cosine and regression analyses were assessed for rhythmicity and correlations.3. The log10CFU of C. jejuni number in the caecal content was the lowest (7.4-8.1) at 10:00 h and highest (9.4-9.8) at 18:00 h. Inoculation status and time points post-inoculation had significant effects on IL-8, IL-18, IL-1β, IgA, IgY and SOCS3 levels (p < 0.001). The IL-8, IL-18, IL-1β and IgY levels at 16 hpi were the lowest compared to other post-inoculated time points.4. The IL-8, IL-1β, IgA and SOCS3 levels of the control and treated groups showed rhythmic changes at 18:00 (p < 0.05). Caecal C. jejuni colonisation was significantly correlated with levels of IL-18, IL-1β, IgA, IgY and SOCS3 (r = 0.35-0.76; p < 0.05), among which IgY had the highest correlation coefficient (r = 0.76; p < 0.0001).5. Chickens were more sensitive to C. jejuni inoculation administered at 18:00 h. Moreover, the changes of IgA, IL-8 and IL-1β levels were lowest at 16 hpi and more likely to show circadian rhythms in chickens inoculated at 18:00 h.