Expression of digestive enzymes and nutrient transporters in Eimeria acervulina-challenged layers and broilers

Abstract

Avian coccidiosis is a disease caused by intestinal protozoa in the genus Eimeria. Clinical signs of coccidiosis include intestinal lesions and reduced feed efficiency and BW gain. This growth reduction may be due to changes in expression of digestive enzymes and nutrient transporters in the intestine. The objective of this study was to examine the differential expression of digestive enzymes, transporters of amino acids, peptides, sugars, and minerals, and an antimicrobial peptide in the small intestine of Eimeria acervulina-infected broilers and layers. Uninfected broilers and layers, in general, expressed these genes at comparable levels. Some differences included 3-fold and 2-fold greater expression of the peptide transporter PepT1 and the antimicrobial peptide LEAP2 (liver expressed antimicrobial peptide 2), respectively, in the jejunum of layers compared with broilers and 17-fold greater expression of LEAP2 in the duodenum of broilers compared with layers. In the duodenum of Eimeria-infected broilers and layers, there was downregulation of aminopeptidase N; sucrase-isomaltase; the neutral, cationic, and anionic amino acid transporters b(o,+)AT/rBAT, B(o)AT, CAT2, and EAAT3; the sugar transporter GLUT2; the zinc transporter ZnT1; and LEAP2. In the jejunum of infected layers there was downregulation of many of the same genes as in the duodenum plus downregulation of PepT1, b(o,+)AT/rBAT, and the y(+) L system amino acid transporters y(+) LAT1 and y(+) LAT2. In the ileum of infected layers there was downregulation of CAT2, y(+)LAT1, the L type amino acid transporter LAT1, and the sugar transporter GLUT1, and upregulation of APN, PepT1, the sodium glucose transporter SGLT4, and LEAP2. In E. acervulina-infected broilers, there were no gene expression changes in the jejunum and ileum. These changes in intestinal digestive enzyme and nutrient transporter gene expression may result in a decrease in the efficiency of protein digestion, uptake of important amino acids and sugars, and disruption of mineral balance that may affect intestinal cell metabolism and Eimeria replication.

Expression of host defense peptides in the intestine of Eimeria-challenged chickens

“…Images were captured using 100x magnification. studies, LEAP2 was down-regulated in all 3 segments of the small intestine (Su et al, 2014(Su et al, , 2015. In this study, ceca were not collected.…”

“…The antimicrobial peptide LEAP2 was down-regulated in the small intestine following challenge with E. acervulina, E. maxima, E. tenella, and E. praecox (Casterlow et al, 2011;Sumners et al, 2011;Paris and Wong, 2013;Su et al, 2014Su et al, , 2015Yin et al, 2015). Using a necrotic enteritis model induced by initial challenge with E. maxima followed by challenge with Clostridium perfringens, Hong et al (2012) reported the expression of HDP in the jejunum of both Cobb and Ross broilers.…”

Expression of digestive enzymes and nutrient transporters in Eimeria-challenged broilers

“…Quantitative real time PCR was performed on an Applied Biosystems 7300 system with SYBR green using the following conditions for all genes: 50°C for 2 min and 95°C for 10 min followed by 40 cycles of 95°C for 15 s and 60°C for 1 min. Samples were run in duplicate and relative gene expression data were analyzed using the 2 −ΔΔCt method (Livak and Schmittgen, 2011) as described in Su et al (2014). β-actin was chosen as the reference gene, because the Ct value for β-actin was the same for control and infected samples.…”

“…Liver-expressed antimicrobial peptide-2 (LEAP2) is an antimicrobial peptide that is part of the innate immune system (Lynn et al, 2004). Recent studies have revealed a downregulation of LEAP2 in chickens infected with E. maxima, E. praecox and E. acervulina (Casterlow et al, 2011;Fetterer et al, 2014;Paris and Wong, 2013;Su et al, 2014;Sumners et al, 2011).…”

“…Fetterer et al (2014) reported a similar decrease in LEAP2, EAAT3 and b 0,+ AT and an increase in LAT1 in E. maxima infected broilers. In E. acervulina-challenged layers and broilers, there was common downregulation of digestive enzymes APN and SI, amino acid transporters b 0,+ AT/rBAT, B 0 AT, EAAT3, CAT2, sugar transporter GLUT2, and zinc transporter ZnT1 in the duodenum (Su et al, 2014). The objective of this study was to compare changes in nutrient transporter and digestive enzyme gene expression in different sections of the small intestine and ceca of broilers following infection with E. acervulina, E. maxima, and E. tenella individually.…”