Interleukin-10 neutralizing antibody for detection of intestinal luminal levels and as a dietary additive in Eimeria challenged broiler chicks.

Interleukin-10 (IL-10) mRNA levels are increased within intestinal mucosa after Eimeria infection. IL-10 apical receptor presence on enterocytes suggests IL-10 is secreted into the intestinal lumen. Increased IL-10 has been shown to be central to the pathogenesis of numerous intracellular pathogens; we hypothesize luminal secretion of IL-10 enables Eimeria spp. infection in chickens. This study examines intestine luminal IL-10 levels and performance in broilers challenged with Eimeria when fed an anti-IL-10 antibody. Chicks were fed a diet (1 to 21 d) with control or anti-IL-10 antibody (0.34 g egg yolk antibody powder/Kg diet) with a saline or 10× dose of Advent coccidiosis vaccine on d 3. One chick per pen was euthanized on days 2, 4, 7, 10, 13, 16, and 19 post-challenge, bled, and intestines were collected for luminal fluid IL-10 concentrations. Body weight and feed intake were measured on d 21, and oocyst shedding was assessed on d 7 post-challenge. A significant Eimeria × antibody interaction on d 21 body weight (P < 0.05) showed chicks fed control antibody, but not anti-IL-10, had significant reductions in body weight when challenged with Eimeria spp. Oocyst shedding was increased with Eimeria challenge, but dietary antibody had no effect. Plasma carotenoid levels were reduced in Eimeria challenged chicks 4, 7, 10, and 16 days post-challenge compared to unchallenged chicks. Lack of an Eimeria × antibody interaction showed anti-IL-10 was not protective against Eimeria-induced decreases in plasma carotenoids. Eimeria challenge increased intestine luminal IL-10 on days 4 and 7 post-challenge in the cecum and jejunum, respectively, compared to unchallenged. Dietary anti-IL-10 decreased luminal IL-10 in the ileum on day 2 post-challenge when compared to control antibody fed chicks. No interaction between Eimeria challenge and antibody was observed on intestine luminal contents of IL-10, suggesting anti-IL-10 was ineffective at preventing increased Eimeria-induced luminal IL-10. In conclusion, Eimeria challenge increased intestinal luminal IL-10 and anti-IL-10 was effective at preventing Eimeria-induced decreased body weight, however the mechanism anti-IL-10 antibody protects body weight during Eimeria challenge remains unknown.