Screening of Optimal CpG-Oligodeoxynucleotide for Anti-Inflammatory Responses in the Avian Macrophage Cell Line HD11

CpG-oligodeoxynucleotides (CpG-ODNs) have been shown to possess immunostimulatory features in both mammals and birds. However, compared to their proinflammatory effects, little is known about the anti-inflammatory responses trig-gered by CpG-ODN in avian cells. Hence, in this study, the anti-inflammatory response in the chicken macrophage cell line HD11 was characterized under stimulation with five types of CpG-ODNs: CpG-A1585, CpG-AD35, CpG-B1555, CpG-BK3, and CpG-C2395. Single-stimulus of CpG-B1555, CpG-BK3, or CpG-C2395 induced interleukin (IL)-10 expression without caus-ing cell injury. The effects of pretreatment with CpG-ODNs before subsequent lipopolysaccharide stimulation were also evaluated. Interestingly, pretreatment with only CpG-C2395 resulted in high expression levels of IL-10 mRNA in the presence of lipopolysaccharide. Finally, gene expression analysis of inflammation-related cytokines and receptors revealed that pre-treatment with CpG-C2395 significantly reduced the mRNA expression of tumor necrosis factor-alpha, IL-1 beta, IL-6, and Toll-like receptor 4. Overall, these results shed light on the anti-inflammatory responses triggered by CpG-C2395 stimulation through a comparative analysis of five types of CpG-ODNs in chicken macrophages. These results also offer insights into the use of CpG-ODNs to suppress the expression of proinflammatory cytokines, which may be valuable in the prevention of avian infec-tious diseases in the poultry industry.