Cytokines of Birds: Conserved Functions—A Largely Different Look

Abstract

Targeted disruptions of the mouse genes for cytokines, cytokine receptors, or components of cytokine signaling cascades convincingly revealed the important roles of these molecules in immunologic processes. Cytokines are used at present as drugs to fight chronic microbial infections and cancer in humans, and they are being evaluated as immune response modifiers to improve vaccines. Until recently, only a few avian cytokines have been characterized, and potential applications thus have remained limited to mammals. Classic approaches to identify cytokine genes in birds proved difficult because sequence conservation is generally low. As new technology and high throughput sequencing became available, this situation changed quickly. We review here recent work that led to the identification of genes for the avian homologs of interferon-alpha/beta (IFN-alpha/beta) and IFN-gamma, various interleukins (IL), and several chemokines. From the initial data on the biochemical properties of these molecules, a picture is emerging that shows that avian and mammalian cytokines may perform similar tasks, although their primary structures in most cases are remarkably different.

Chicken genome: Current status and future opportunities

“…Since then, there has been slow progress in the isolation of avian cytokines and other signaling molecules. The main problem has been their high rate of evolution, limiting their detection using homology to mammalian sequences (Staeheli et al 2001). Even now, one must be careful in concluding that avian homologs to mammalian immune genes do not exist, as several examples known from ESTs or directed sequencing were not found in the genome assembly.…”

“…This started to change when analysis of large EST data sets identified 185 immune-related sequences (Lynn et al 2003;Smith et al 2004). This compared with the 80 genes identified by Tirunagaru et al (2000) and the 28 genes listed in the review by Staeheli et al (2001). Sequences included interleukins, transcription factors, chemokines, differentiation antigens, receptors, genes involved in the Toll pathway, and MHC-associated genes.…”

“…Sequences included interleukins, transcription factors, chemokines, differentiation antigens, receptors, genes involved in the Toll pathway, and MHC-associated genes. The discovery of IL4 and other cytokines involved in the Th2 response ) was a surprise, since it had previously been speculated that the chicken does not elicit a typical Th2 response (Staeheli et al 2001). The receptors for IL10 and IL13 were also identified, indicating that the chicken probably also contained these genes, which are typical Tr1 and Th2 cytokines.…”

GUT IMMUNITY IN BIRDS: FACTS AND REFLECTIONS (review)

“…IL1 is the major mediator of inflammation in mammals and birds; it is synthesized primarily by monocytes and tissue macrophages (115,116), as well as by other cells including enterocytes (117)(118)(119)(120). In chickens, IL1 participates in inflammatory responses caused by bacterial infection or LPS stimulation; IL1 induces fever (high body temperature) and chemokine production (115,116). Comparing the synthesis of IL1 mRNA immediately post-hatch and two days later, it remained almost unchanged in the colon and in ceca, while increased almost twice in the duodenum on the 2 nd day of life (probably, due to the first feeding and bacterial colonization in the gut) (121, 122).…”

Recent Progress in Understanding Host Mucosal Response to Avian Coccidiosis and Development of Alternative Strategies to Mitigate the Use of Antibiotics in Poultry Production

“…In contrast to the plethora of mammalian cytokines, only a few chicken homologs have been described, the major ones including IFN-γ, IL-1, 2, 6 (Schneider et al, 2001), 8, and15 (Lillehoj et al, 2004;Staeheli et al, 2001). More recently, a series of new chicken cytokines have been described, inclu-ding IL-17 (Min and Lillehoj, 2002), 18 (Schneider et al, 2000), 16 Production of chicken IL-6-like activity was detected in serum taken from chickens infected with E. tenella during the course of a primary infection (Lynagh et al, 2000).…”