Submitted to: Developmental and Comparative Immunology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/27/2008
Publication Date: 3/24/2008
Citation: He, H., Genovese, K.J., Nisbet, D.J., Kogut, M.H. 2008. Phospholipase C, phosphatidylinositol 3-kinase, and intracellular [Ca2+] are involved in activation of chicken HD11 macrophage by CpG oligodeoxynucleotide. Developmental and Comparative Immunology. 32(10):1111-1118.
Interpretive Summary: CpG ODN is a component of bacteria DNA. Macrophage cells are one type of the white blood cells found in chickens. The macrophage cells can produce nitric oxide, a chemical that can kill bacteria and protects chickens from infection by pathogenic bacteria such as Salmonella. We have performed experiments to see if and how the macrophage cells produce bacteria-killing nitric oxide when they are exposed to the CpG ODN. We found that the chicken macrophages can produce nitric oxide after contact with CpG ODN. We also found that phospholipase C and several other molecules are the components of cell machinery that control the chemical processes to produce the nitric oxide in the macrophage cells. This information is important to the pharmaceutical and poultry industries in the United States because it shows us that we can possibly manipulate the chicken immune system and produce healthier chickens.
Technical Abstract: The activation of phospholipases is one of the earliest key events in receptor-mediated cellular responses to a number of extracellular signaling molecules. Oligodeoxynucleotides containing CpG motifs (CpG ODN) mimic microbial DNA and are immunostimulatory to most vertebrate species. In the present study, we used the production of nitric oxide (NO) as a indicator to evaluate the involvement of the signaling cascades of phospholipases and phosphatidylinositol 3-kinase (PI3K) in the activation of chicken HD11 macrophage cells by CpG ODN. Using selective inhibitors, we have identified the involvement of phosphatidylinositol (PI)-phospholipase C (PI-PLC), but not phosphatidylcholine (PC)-phospholipase C (PC-PLC) and PC-phospholipase D (PC-PLD), in CpG ODN-induced NO production in HD11 cells. Preincubation with PI-PLC selective inhibitors (U-73122) completely abrogated CpG ODN-induced NO production in HD11 cells, whereas PC-PLC inhibitor (D609) and PC-PLD inhibitor (n-butanol) had no inhibitory effects. Additionally, inhibition of phosphatidylinositol 3-kinase (PI3K) and protein kinase C (PKC) with selective inhibitors and chelation of intracellular [Ca2+] also significantly attenuated NO production in CpG ODN-activated HD11 cells. Our results demonstrate that PI-PLC, PI3K, PKC, and intracellular [Ca2+] are important components of CpG ODN-induced signaling pathway that leads to production of NO in avian macrophage cells.