|Tan, Jianzhuang -|
|Applegate, Todd -|
|Liu, Shasha -|
|Guo, Yuming -|
Submitted to: British Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 10, 2014
Publication Date: January 13, 2014
Citation: Tan, J., Applegate, T.J., Liu, S., Guo, Y., Eicher, S.D. 2014. Supplemental dietary L-arginine attenuates intestinal mucosal disruption during a coccidial vaccine challenge in broiler chickens. British Journal of Nutrition. http://dx.doi.org/10.1017/S0007114514001846. Interpretive Summary: The present study investigated the effects of dietary arginine (Arg) supplementation on intestinal barrier integrity in broiler chickens undergoing an infection with a common intestinal pathogen (coccidia). Within 7 days chickens decreased body weight gain and feed intake, which resulted in more feed necessary for gain in the coccidiosis-challenged chickens. Coccidiosis-challenged chickens demonstrated greater mucosal secretory IgA and IgG concentrations in the gut, greater expression of gut inflammatory genes and increasing Arg reduced overexpression of some of those genes. The intestinal inflammation was evidenced by villus damage, crypt dilation, and depletion of goblet cell (mucin producing cells) and Arg increased intestinal villus height and the expression of pathway genes and an anti-apoptosis gene (anti-cell death, Bcl-2). Additionally, dietary Arg deficiency decreased intestinal goblet cell density. These results indicate that Arg supplementation preserved intestinal barrier integrity of coccidiosis-challenged chickens.
Technical Abstract: The present study investigated the effects of dietary arginine (Arg) supplementation on intestinal barrier integrity in broiler chickens undergoing coccidial challenge. The design of this study was a randomized complete block employing a 3 x 2 factorial arrangement (n = 8) with 3 level of Arg (1.11, 1.33, and 2.02) and 2 level of coccidial vaccine challenge (control and coccidial challenge). On day 14, birds were gavaged with coccidial vaccine (20 x) or saline. Birds were killed on day 21 to obtain jejunal tissue and mucosal samples for histology, gene expression and mucosal immunity measurements. Within 7 days of challenge, coccidial challenge decreased BW gain and feed intake, increased feed-to-gain of coccidiosis-challenged chickens (P < 0.05). Coccidiosis-challenged chickens demonstrated greater mucosal secretory IgA and IgG concentrations, higher jejunal inflammatory genes (iNOS, IL-1 beta, IL-8, TLR4 and MyD88) mRNA expression (P < 0.05). The jejunal inflammation was evidenced by villus damage, crypt dilation, and goblet cell depletion. Increasing Arg concentration: (a) linearly and quadratically (P < 0.05) suppressed over expression of TLR4 mRNA in coccidiosis-challenged chickens, and tended to decrease MyD88 and IL-1 beta mRNA expression (P < 0.10); (b) increased jejunal villus height and the mRNA expression of mTOR complex 1 pathway genes (mTOR, RPS6KB1 and Raptor) and anti-apoptosis gene Bcl-2 (P < 0.05). Additionally, dietary Arg deficiency (1.11 ) decreased jejunal goblet cell density (per mm of villi; P < 0.05). These results indicate that Arg supplementation preserved intestinal barrier integrity of coccidiosis-challenged chickens probably through suppressing TLR4/MyD88 and activating roTOR complex1 pathways.