Distinct regulatory roles of NF-kB in CpGA and CpGB-induced IFN-alpha production by plasmacytoid dendritic cells (135.50)

Abstract Plasmacytoid dendritic cells (PDC) are a major source of IFN-α production in response to the TLR9 ligand CpGA, but not CpGB. TLR9, MyD88, and IRF7 have been established to be in the major pathway of PDC IFN-α production. We found that the inhibition of NF-κB activation by SN50 or NBD conferred on CpGB the ability to induce IFN-α in PDC, while CpGA-induced IFN-α was decreased. Using the ImageStream imaging flow cytometer, we found that although CpGA-induced IRF-7 translocation was inhibited by SN50, SN50 conferred the ability of CpGB to induce IRF7 nuclear translocation. The early endosomal localization of CpG has been shown to be important in IFN-α production. We found that both CpGA and CpGB moved from early to late endosomes from 30 min to 2 hr. However, neither CpGA nor CpGB was found in either early or late endosomes in large quantities upon NF-κB inhibition. Unlike in cell lines, in PDC, TLR9 was found to be constitutively localized in the early endosomes and also recruited from ER upon stimulation with CpGA. These results suggest that NF-κB plays an inverse role in the regulation of IFN-α production by PDC in response to CpGA or CpGB stimulation. Supported by AI26806.