CpG-C Immunostimulatory Oligodeoxyribonucleotide Activation of Plasmacytoid Dendritic Cells in Rhesus Macaques to Augment the Activation of IFN-γ-Secreting Simian Immunodeficiency Virus-Specific T Cells

Abstract

There are two principle subsets of dendritic cells (DCs); CD11c+CD123− myeloid DCs (MDCs) and CD11c−CD123+ plasmacytoid DCs (PDCs). DC activation via TNF-TNFRs (e.g., CD40L) and TLRs (e.g., immunostimulatory oligodeoxyribonucleotides (ISS-ODNs)) is crucial for maximal stimulation of innate and adaptive immunity. Macaque DC biology is being studied to improve HIV vaccines using the SIV macaque model. Using lineage (Lin) markers to exclude non-DCs, Lin−HLA-DR+CD11c+CD123− MDCs and Lin−HLA-DR+CD11c−CD123+ PDCs were identified in the blood of uninfected macaques and healthy macaques infected with SIV or simian-human immunodeficiency virus. Overnight culture of DC-enriched Lin-depleted cells increased CD80 and CD86 expression. IL-12 production and CD80/CD86 expression by MDC/PDC mixtures was further enhanced by CD40L and ISS-ODN treatment. A CpG-B ISS-ODN increased CD80/CD86 expression by PDCs, but resulted in little IFN-α secretion unless IL-3 was added. In contrast, a CpG-C ISS-ODN and aldrithiol-2-inactivated (AT-2) SIV induced considerable PDC activation and IFN-α release without needing exogenous IL-3. The CpG-C ISS-ODN also stimulated IL-12 release (unlike AT-2 SIV) and augmented DC immunostimulatory activity, increasing SIV-specific T cell IFN-γ production induced by AT-2 SIV-presenting MDC/PDC-enriched mixtures. These data highlight the functional capacities of MDCs and PDCs in naive as well as healthy, infected macaques, revealing a promising CpG-C ISS-ODN-driven DC activation strategy that boosts immune function to augment preventative and therapeutic vaccine efficacy.

Local and Systemic Effects of Intranodally Injected CpG-C Immunostimulatory-Oligodeoxyribonucleotides in Macaques

“…Previous studies showed that CpG-B ISS-ODNs boosted vaccine efficacy in nonhuman primates (49 -55), but until recently there were no reports of CpG-C ISS-ODN usage in macaques (56). We found that the CpG-C ISS-ODN C274 activates macaque blood-derived DCs (17) and B cells (57) in vitro. This is supported by a recent report from Abel et al (58), documenting the responses of macaque blood and lymphoid PDCs to the different classes of CpG ISS-ODNs.…”

“…As in humans, there are two major subsets of DCs present in macaque blood and LNs, myeloid CD11c ϩ CD123 Ϫ (myeloid DCs; MDCs) and plasmacytoid CD11c Ϫ CD123 ϩ (plasmacytoid DCs; PDCs) DCs (14 -17). DCs readily capture SIV and HIV (18,19) and immunodeficiency viruses can trigger innate PDC responses (17,20). However, interaction of these viruses with DCs is a double-edged sword.…”

“…However, interaction of these viruses with DCs is a double-edged sword. DCs play a critical role in initiating and coordinating antiviral immune responses, with mature DCs typically inducing stronger virus-specific responses (17,(21)(22)(23)(24). In contrast, these viruses seem to have developed replication strategies that subvert DC biology (19,25,26).…”

“…infected with SHIV162P4 on 2/8/99. T cells from these animals secrete IFN-␥ in response to chemically inactivated SIV (aldrithiol-2 (AT-2) SIV) in vitro (our unpublished observation) (17).…”

Characterization of Virus-Responsive Plasmacytoid Dendritic Cells in the Rhesus Macaque

“…Others have reported that macaque PDC, like their human counterparts, can be identified by using four markers: lineage, HLA-DR, CD123, and CD11c (8,48). We demonstrate here that the macaque PDC, like their human counterparts, can be identified by using our two-color scheme (9), which utilizes CD123 and HLA-DR only.…”