Submitted to: Journal of Innate Immunity
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/5/2009
Publication Date: 1/18/2010
Citation: He, L.H., Mackinnon, K.M., Genovese, K.J., Kogut, M.H. 2010. CpG oligodeoxynucleotide and double-stranded RNA synergize nitric oxide production and mRNA expression of inducible nitric oxide synthase, pro-inflammatory cytokines, and chemokines in chicken monocytes. Journal of Innate Immunity. 16:1-8.
Interpretive Summary: DNA and RNA are nucleic acids that make up the genetic blueprint of life and control chemical reactions in all cells. Monocytes are one type of white blood cells found in chickens. These monocytes can recognize bacterial DNA and viral RNA and produce chemicals that can kill bacteria and virus. These bacteria- and virus-killing chemicals help chickens fight infections and therefore stay healthy. CpG-ODN and poly I:C are two synthetic chemicals that are similar to the bacterial DNA and viral RNA, respectively. We have performed experiments to see if chicken monocytes produce bacteria- and virus-killing chemicals when they are exposed to CpG-ODN and poly I:C. We found that chicken monocytes are able to recognize CpG-ODN and poly I:C and produce bacteria- and virus-killing chemicals, such as nitric oxide, cytokines, and chemokines. We have also found that chicken monocytes can produce significantly more of these chemicals when they are exposed to both CpG-ODN and poly I:C at the same time. This information is important to the pharmaceutical and poultry industries in the United States because it may offer a new method of producing healthy chickens and reduce the use for antibiotics.
Technical Abstract: Toll-like receptors (TLRs) recognize microbial components and initiate the innate immune responses that control microbial infections. The interaction between ligands of TLR3 and TLR9, poly I:C (an analog of viral double-stranded RNA), and CpG-ODN (a CpG-motif containing oligodeoxydinucleotide) on the inflammatory immune responses, including the production of nitric oxide (NO) and the expression of inducible NO synthase (iNOS), proinflammatory cytokines Interleukin (IL)-1ß and IL-6, and chemokines IL-8 and macrophage inflammatory protein (MIP)-1ß, were investigated in chicken monocytes. The NO production was significantly higher (39.4 µM) when stimulated with a combination of CpG-ODN (5 µg/ml) and poly I:C (20 µg/ml) than with either CpG-ODN (8.4 µM) or poly I:C (0.5 µM) alone. After a combinatory stimulation with CpG-ODN and poly I:C, the expression of iNOS mRNA in chicken monocytes increased 348-, 1338-, 797-, and 213-fold after 2, 4, 8, and 24 hr of stimulation, respectively, which was significantly higher than stimulation with either CpG-ODN (105-, 223-, 87-, and 23-fold) or poly I:C (19-, 67-, 6-, and 2-fold) alone. Similarly, compared to either CpG-ODN or poly I:C alone, a combinatory stimulation resulted in significantly larger increases in expression of IL-1ß (53-, 47-, 46-, and 17-fold), IL-6 (15-, 18-, 13-, and 22-fold), IL-8 (2923-, 1200-, 785-, and 1048-fold), and MIP-1ß (13-, 12-, 8-, and 24-fold) after 2, 4, 8, and 24 hr of stimulation, respectively. Our results demonstrated that CpG-ODN and poly I:C differentially, but synergistically when used in combination, induced proinflammatory immune response in chicken monocytes.