Comparative expression of host defense peptides in turkey poults

Abstract

Host defense peptides (HDPs) are a large group of small, positively charged peptides that play an important role in innate immunity, particularly at early ages when other components of the immune system have not fully developed. There are 3 classes of avian HDPs: avian beta defensins (AvBDs), cathelicidins (Cath), and liver-expressed antimicrobial peptide 2 (LEAP-2). The objective was to compare expression of HDP mRNAs in male turkey poults at day of hatch (d 0), d 7, d 14, d 21 and d 28 from the thymus, spleen, bursa, duodenum, jejunum, and ileum. The expression of AvBD1, AvBD2, AvBD8, AvBD9, AvBD10, AvBD13, Cath2, Cath3, and LEAP-2 mRNA was measured using qPCR (n = 6 birds/tissue/age). Data were analyzed by one-way ANOVA and Tukey's test, and significance considered at P < 0.05. AvBDs and Caths exhibited greater expression in immune organs (thymus, spleen, and bursa) than intestinal tissues. In the thymus, expression of all AvBDs examined, except AvBD8, showed an increase from d 0 to d 21. In the spleen, AvBD1 and AvBD2 exhibited reduced expression from d 0 to d 7 and low expression thereafter. In the intestine, AVBD1, AVBD8, and AvBD13 increased expression from d 0 to d 28 in the duodenum, while AvBD10 showed the greatest expression at d 0 that declined to d 7 and stayed low thereafter in the duodenum, jejunum, and ileum. Cath2 and Cath3 demonstrated the highest expression in the spleen, which was greatest at d 0 then declined to d 7 through d 28. Conversely, LEAP-2 showed greater expression in the intestinal tissues than in the immune organs. LEAP-2 expression was upregulated from d 0 to d 7 and then remained elevated from d 7 through d 14 in the duodenum. In the jejunum, LEAP-2 increased from d 0 to d 21 and d 28. Understanding the differential expression of HDPs could reveal the innate immune status of turkey poults, and may subsequently allow improvement of their health through appropriate mitigation strategies.

Expression and regulation of avian beta-defensin 8 protein in immune tissues and cell lines of chickens

“…Moreover, Xiao et al [ 5 ] reported high AvBD8 gene expression only in the liver of 8-week-old healthy chickens. Recently, Hamad et al [ 15 ] reported high AvBD8 gene expression in the thymus, spleen, and bursa of 3- to 4–week-old healthy male turkeys. These studies suggest that AvBD8 gene/protein expression is high in young birds and decreases in aged birds.…”

Colonization, spread and persistence of Salmonella (Typhimurium, Infantis and Reading) in internal organs of broilers

“…Spleen, as the secondary immune organ not only functions as blood filtration, but also is a key immune organ for systemic antigen sampling and mounting appropriate humoral and/or cell-mediated immune responses ( Smith and Hunt, 2004 ). Hamad et al (2017) reported that host-defense peptides play a key role in the innate immunity components with direct antimicrobial activities and immunomodulatory properties in poultry species. Exposing the chicks to a high Salmonella population (8 log CFU/g) as in the H dose challenge possibly could trigger a more acute immune response and upregulation of related immune genes such as avian beta-defensins and cathelicidins.…”

Antimicrobial Peptides: An Update on Classifications and Databases

“…In chickens, chCATH B1, isolated from a specialized organ for hematopoiesis and B cell development (the avian bursa of Fabricius), is a potential antimicrobial against S. aureus , P. aeruginosa , and E. coli [ 275 ]. Cathelicidin-like-peptides have also been found in common quail (cathelicidin Cc-CATH1, 2, and 3 from Coturnix coturnix ) [ 276 ], Japanese quail (Cj-CATH-1, -2, -3, and -B1 from Coturnix japonica ) [ 277 ], rock pigeon (Cl-CATH2 and 3 from Columba livia ) [ 278 ], duck (dCATH from Anas platyrhynchos ) [ 279 ], pheasant (Pc-CATH1, 2, and 3 from Phasianus colchicus ) [ 280 ], and turkey (CATH2 and 3 from Meleagris gallopavo ) [ 281 , 282 ].…”