Recent progress in the understanding of host immunity to avian coccidiosis: IL-17 family cytokines as the sentinels on the intestinal mucosa

Authors: MIN, WONGI - Gyeongsang National University; KIM, WOO - Gyeongsang National University; Lillehoj, Hyun

Submitted to: Developmental and Comparative Immunology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/2/2013
Publication Date: 9/20/2013
Publication URL: http://handle.nal.usda.gov/10113/59002
Citation: Min, W., Kim, W.H., Lillehoj, H.S. 2013. Recent progress in the understanding of host immunity to avian coccidiosis: IL-17 family cytokines as the sentinels on the intestinal mucosa. Developmental and Comparative Immunology. 41(3):418-28. doi: 10.1016/j.dci.2013.04.003.

Interpretive Summary: Understanding the complex interplay among various components of host immune system is critical to develop effective disease prevention strategies against poultry enteric diseases like coccidiosis. One of the current challenges of avian coccidiosis research is to identify the cellular and molecular basis for species-specific immunity and a potential cross-protective immune mechanism that could confer protection against several species of Eimeria. Furthermore, the role of various soluble factors involved in local inflammatory response needs to be better characterized in view of the negative consequences of uncontrolled inflammation on gut health and poultry productivity. In this review paper, an ARS scientist in collaboration with scientists at a Korean university reviewed current literature to summarize the current knowledge on chicken immunity to avian coccidiosis with special emphasis on the role of IL-17 family cytokines in the gut defense against intracellular parasitism. This review will help industry and other scientists to understand the importance of IL-17 family cytokines in coccidiosis resistance and this new information may lead to a new immune modulation strategy to reduce economic losses due to avian coccidiosis.

Technical Abstract: Host-pathogen interaction leading to protection against coccidiosis is complex, involving many aspects of innate and adaptive immunity to intracellular parasites. Innate immunity is mediated by various subpopulations of innate immune cells through the secretion of soluble factors with diverse functions upon the recognition of the pathogen associated molecular patterns by the host pattern recognition receptor molecules. Adaptive immunity, which is important in conferring protection against subsequent infections, involves many subtypes of T and B lymphocytes that mediate antigen-specific immune responses. Recent application of global gene expression microarray analysis to investigate gut innate immune response to Eimeria infections led to the discovery of many novel host genes modulated by different life cycle stages of coccidian parasites. Furthermore, these new findings illustrated the uniqueness of the innate immune response to Eimeria and the role of many innate immune cells and their secreted proinflammatory cytokines which influence the local host-parasite interactions in avian coccidiosis. Lately, a new type of T lymphocytes which secretes IL-17 family cytokines has been shown to influence local inflammation and mediates host defense against gut pathogens on the mucosal surface. In avian coccidiosis, IL-17 secretion was induced in the intestinal intraepithelium where Eimeria parasites undergo intracellular development during the early phase of host response to coccidiosis. Furthermore, the level of IL-17 response correlates with genetically determined coccidiosis disease resistance. In view of IL-17 family cytokine role in inflammation and in local defense against invading pathogens including parasites, understanding their biological function in avians and their potential role in host defense against intestinal parasitism will be important in developing a new strategy against avian coccidiosis.