Introduction: Plasmacytoid dendritic cells (pDCs) play not only a central role in the antiviral immune response in innate host defense, but also a pathogenic role in the development of the autoimmune process by their ability to produce robust amounts of type I interferons (IFNs), through sensing nucleic acids by toll-like receptor (TLR) 7 and 9. Thus, control of dysregulated pDC activation and type I IFN production provide an alternative treatment strategy for autoimmune diseases in which type I IFNs are elevated, such as systemic lupus erythematosus (SLE). Here we focused on IkappaB kinase inhibitor BAY 11-7082 (BAY11) and investigated its immunomodulatory effects in targeting the IFN response on pDCs.
Methods: We isolated human blood pDCs by flow cytometry and examined the function of BAY11 on pDCs in response to TLR ligands, with regards to pDC activation, such as IFN-alpha production and nuclear translocation of interferon regulatory factor 7 (IRF7) in vitro. Additionally, we cultured healthy peripheral blood mononuclear cells (PBMCs) with serum from SLE patients in the presence or absence of BAY11, and then examined the inhibitory function of BAY11 on SLE serum-induced IFN-alpha production. We also examined its inhibitory effect in vivo using mice pretreated with BAY11 intraperitonealy, followed by intravenous injection of TLR7 ligand poly U.
Results: Here we identified that BAY11 has the ability to inhibit nuclear translocation of IRF7 and IFN-alpha production in human pDCs. BAY11, although showing the ability to also interfere with tumor necrosis factor (TNF)-alpha production, more strongly inhibited IFN-alpha production than TNF-alpha production by pDCs, in response to TLR ligands. We also found that BAY11 inhibited both in vitro IFN-alpha production by human PBMCs induced by the SLE serum and the in vivo serum IFN-alpha level induced by injecting mice with poly U.
Conclusions: These findings suggest that BAY11 has the therapeutic potential to attenuate the IFN environment by regulating pDC function and provide a novel foundation for the development of an effective immunotherapeutic strategy against autoimmune disorders such as SLE.