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

Authors: RENGARAJ, DEIVENDRAN - Chung-Ang University; TRUONG, ANH DUC - Chung-Ang University; Lillehoj, Hyun; HAN, JAE YONG - Seoul National University; HONG, YEONG HO - Chung-Ang University

Submitted to: Asian-Australasian Journal of Animal Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/5/2018
Publication Date: 9/1/2018
Citation: Rengaraj, D., Truong, A., Lillehoj, H.S., Han, J., Hong, Y. 2018. Expression and regulation of avian beta-defensin 8 protein in immune tissues and cell lines of chickens. Asian-Australasian Journal of Animal Sciences. https://doi.org/10.5713/ajas.17.0836.
DOI: https://doi.org/10.5713/ajas.17.0836

Interpretive Summary: Limited information on poultry defense immune system hinders progress in developing immune modulation strategies that can replace antibiotics. Poultry immune system comprises the innate and adaptive immune systems where the innate immune system includes immune cells, antimicrobial peptides, enzymes, and proinflammatory factors that are involved in the immediate defensive host response against harmful pathogens. In this report, ARS scientists collaborated with scientists at a Korean university to investigate host defensins which are a large family of antimicrobial peptides found in vertebrates. Defensins play a crucial role in inducing innate immunity that protect hosts from various pathogens. This paper reports that birds have 14 different beta-defensins and one of them, AvBD8, is expressed in the thymus, spleen, liver, intestine, and ceca of healthy White Leghorn (WL) chickens. Furthermore, AvBD8 is involved in host response against necrotic enteritis (NE) which was induced by by dual infection of chickens with Eimeria maxima and Clostridium perfringens. The information provided in this paper will be used to design further studies to test the efficacies of various defensins as novel immunotherapeutics to reduce the use of antibiotics in animal agriculture.

Technical Abstract: Objective: Defensins are a large family of antimicrobial peptides and components of the innate immune system that invoke an immediate immune response against harmful pathogens. Defensins are classified into alpha-, beta-, and theta-defensins. Avian species only possess beta-defensins (AvBDs), and approximately 14 AvBDs (AvBD1 -AvBD14) have been identified in chickens to date. Although substantial information is available on the conservation and phylogenetics, limited information is available on the expression and regulation of AvBD8 in chicken immune tissues and cells. Methods: We examined AvBD8 protein expression in immune tissues of healthy White Leghorn chickens (WL) and AvBD8 regulation in the intestine of inbred WL chickens with necrotic enteritis by immunohistochemistry. In addition, we examined AvBD8 expression in chicken T-, B-, macrophage-, and fibroblast-cell lines and its regulation in these cells after lipopolysaccharide (LPS) treatment by immunocytochemistry and quantitative real-time PCR. Results: Our results showed that chicken AvBD8 protein was strongly expressed in the healthy WL intestine and in macrophages. AvBD8 gene expression was highly upregulated in macrophages treated with different LPS concentrations compared with that in T- and B-cell lines in a time-independent manner. Moreover, chicken AvBD8 strongly interacted with other AvBDs and with other antimicrobial peptides as determined by bioinformatics. Conclusion: Our study provides the expression and regulation of chicken AvBD8 protein in immune tissues and cells, which play crucial role in the innate immunity.