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Title: Molecular Cloning and Characterization of Chicken Lipopolysaccharide-Induced TNF-alpha Factor (LITAF)

item Lillehoj, Hyun

Submitted to: Developmental and Comparative Immunology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/20/2007
Publication Date: 4/30/2007
Citation: Hong, Y.H., Lillehoj, H.S., Lee, S.H., Park, D.W., Lillehoj, E.P. 2007. Molecular Cloning and Characterization of Chicken Lipopolysaccharide-Induced TNF-alpha Factor (LITAF). Developmental and Comparative Immunology 30:919-929.

Interpretive Summary: This is a CSREES NRI-funded project to develop new strategies to reduce economic losses due to salmonellosis and coccidiosis. The short-term goals of this proposal included expanding our basic understanding of the function of macrophages in avian enteric diseases In this report, we describe identification of an important soluble protein called LPS-induced TNF factor (LITAF) which is released from macrophages upon activation by coccidia parasites. The gene which encodes this protein was cloned full length and recombinant LITAF protein was expressed in various expression system. The results show that the recombinant LITAF was produced high level in the gut during coccidiosis and may be involved in coccidiosis-induced pathology in the gut. This information will help in our understanding of parasite-mediated immunopathology and to the development of new strategy to reduce economic loss due to coccidiosis in poultry.

Technical Abstract: The inflammatory response to parasites, bacteria, and viruses is mediated by multiple host factors. TNF-alpha is one of the most pleiotropic cytokines in mammals, but has yet to be identified in avian species. In the current study, we isolated a full-length cDNA encoding the chicken homologue of LPS-induced TNF-alpha factor (LITAF), transcription factor, with an open reading frame of 148 amino acids and a predicted molecular mass of 16.0 kDa. Quantitative RT-PCR analysis showed that chicken LITAF mRNA was predominantly expressed in spleen and intestinal intraepithelial lymphocytes (IELs). LITAF mRNA levels were up-regulated following in vitro stimulation of macrophages for 4 hr with Escherichia coli or Salmonella typhimurium endotoxin, and 18-48 hr after treatment with Eimeria acervulina, E. maxima, or E. tenella, three causative agents of avian coccidiosis. LITAF mRNA was up-regulated more than 700-fold in IELs isolated from E. maxima-infected birds. Purified recombinant LITAF protein expressed in E. coli or COS7 cells exhibited cytotoxic activity against chicken tumor cell lines in vitro, presumably through autocrine activation of TNF-alpha or its chicken homologue. This supposition was strengthened by the fact that treatment of chicken macrophages with recombinant LITAF induced the expression of TL1A (TNFSF 15), a member of the TNF ligand super family. We conclude that chicken LITAF may play an important role in the regulation of TNF-alpha gene expression during the course of coccidiosis or tumorigenesis.