Modulation of the spleen transcriptome in domestic turkey (Meleagris gallopavo) in response to aflatoxin B1 and probiotics

Abstract

Poultry are highly susceptible to the immunotoxic effects of the food-borne mycotoxin aflatoxin B1 (AFB1). Exposure impairs cell-mediated and humoral immunity, limits vaccine efficacy, and increases the incidence of costly secondary infections. We investigated the molecular mechanisms of AFB1 immunotoxicity and the ability of a Lactobacillus-based probiotic to protect against aflatoxicosis in the domestic turkey (Meleagris gallopavo). The spleen transcriptome was examined by RNA sequencing (RNA-seq) of 12 individuals representing four treatment groups. Sequences (6.9 Gb) were de novo assembled to produce over 270,000 predicted transcripts and transcript fragments. Differential expression analysis identified 982 transcripts with statistical significance in at least one comparison between treatment groups. Transcripts with known immune functions comprised 27.6 % of significant expression changes in the AFB1-exposed group. Short exposure to AFB1 suppressed innate immune transcripts, especially from antimicrobial genes, but increased the expression of transcripts from E3 ubiquitin-protein ligase CBL-B and multiple interleukin-2 response genes. Up-regulation of transcripts from lymphotactin, granzyme A, and perforin 1 could indicate either increased cytotoxic potential or activation-induced cell death in the spleen during aflatoxicosis. Supplementation with probiotics was found to ameliorate AFB1-induced expression changes for multiple transcripts from antimicrobial and IL-2-response genes. However, probiotics had an overall suppressive effect on immune-related transcripts.

Aflatoxicosis: Lessons from Toxicity and Responses to Aflatoxin B1 in Poultry

“…Similar to expression changes in other species, transcriptome analysis in the turkey found that more genes were up-regulated than down-regulated by AFB1 [227,238,240]. In one study of the liver, more than 80 genes belonging to cancer or focal adhesion pathways were up-regulated during aflatoxicosis, whereas smaller numbers of genes involved in cell signaling, cytoskeleton, and cell cycle were also up-regulated [227].…”

“…Although some genes are well characterized, the functions and expression patterns of many poultry MHC genes are still unknown. In the turkey, expression of multiple MHC genes significantly increased in response to AFB1 exposure [238].…”

“…More recently, RNA-seq has been applied to the domestic turkey transcriptome to elucidate hepatic and splenic responses to dietary AFB1 [227,238,240]. Similar to expression changes in other species, transcriptome analysis in the turkey found that more genes were up-regulated than down-regulated by AFB1 [227,238,240].…”

Broiler Tavuklarda Aflatoksin ile Kontamine Diyette Ticari Toksin Bağlayıcı, Doğal Probiyotik Türleri, Maya Hücre Duvarı ve Aluminosilikatın GOT2 ve CYP450 1A5 Gen Ekspresyonları İle Karaciğer Enzimlerinin Serum Konsantrasyonları Üzerine Etkisi

“…Investigating the results of changes in liver enzymes gene expression indicated that increase in gene expression related to interleukins, liver enzymes and especially enzymes involved in the metabolism of aflatoxin occurs under the influence of aflatoxin [28] . It seems that changes in gene expression levels in the liver occurs by using aflatoxin contaminated diets therefore acute and chronic aflatoxicosis occur due to the liver proliferation 2 [12] . Studies on the impact of diets contaminated with aflatoxin on gene expression in liver enzymes showed that the presence of toxin in the diet causes to upregulation of CYP450 1A gene.…”

“…Due to the limitations of aluminosilicate consumption, using biological compounds is on the agenda of nutritionists because of their numerous advantages. It has been proved that using diets based on the probiotic compounds especially Lactobacilli in poultry diets, have the ability to reduce aflatoxin effects on the gene expression of liver enzymes such as genes for amino acids and fat metabolizing enzymes [12] . Gao et al [13] found the high ability of Bacillus Subtilis for reducing the effects or disable B 1 , M 1 and G 1 aflatoxins.…”