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

Abstract

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.

Keywords: Eimeria; Interleukin-10; anti-IL-10; coccidiosis; egg antibody.

Figure 1.

The neutralizing effects of affinity purified egg yolk anti-IL-10 antibody were determined by measuring the ability of recombinant chicken IL-10 to inhibit IFN-γ production in Concanavalin A (Con A) stimulated chicken splenocytes. Splenocytes were untreated, stimulated with 20 μg Con A, stimulated with Con A and 0.2 ng/mL, recombinant chicken IL-10, or stimulated with Con A, IL-10, and 0.85 μg/mL affinity purified egg anti-IL-10 specific antibody. Culture media was analyzed for IFN-γ 24 hours after treatment. Anti-IL-10 was effective at neutralizing IL-10s inhibition of IFN-γ release (overall ANOVA P < 0.0001, standard error of the mean bars n = 3). ^a–dTreatment means with different letter superscripts are statistically different (P < 0.05).

Figure 2.

Intestinal luminal IL-10 of Eimeria challenged chicks. Only the main effect of Eimeria challenge is shown for duodenum (2A), jejunum (2B), ileum (2C), cecum (2D) at each time point sampled. Main effect of antibody is shown for the ileum (2E). Error bars denote standard error of the mean (n = 20/treatment).

Figure 3.

Plasma carotenoid levels of Eimeria challenged chicks. Within each day post challenge *denote significant difference between unchallenged and challenged treatment groups (P < 0.05). Error bars represent the standard error of the mean (n = 20/treatment).