Coadministration of Polyinosinic:Polycytidylic Acid and Immunostimulatory Complexes Modifies Antigen Processing in Dendritic Cell Subsets and Enhances HIV Gag-Specific T Cell Immunity

Abstract

Currently approved adjuvants induce protective antibody responses but are more limited for generating cellular immunity. Here we assessed the effect of combining two adjuvants with distinct mechanisms of action on their ability to prime T cells; the TLR3 ligand, polyinosinic:polycytidylic acid (Poly I:C), and immunostimulatory complexes (ISCOMs). Each adjuvant was administered alone or together with HIV Gag protein (Gag) and the magnitude, quality and phenotype of Gag-specific T cell responses were assessed. For CD8 T cells, all adjuvants induced a comparable response magnitude, but combining Poly I:C with ISCOMs induced a high frequency of CD127+, IL-2 producing cells with decreased expression of Tbet compared to either adjuvant alone. For CD4 T cells, combining Poly I:C and ISCOMs increased the frequency of multifunctional cells, producing IFNγ, IL-2 and TNF, and the total magnitude of the response compared to either adjuvant alone. CD8 or CD4 T cell responses induced by both adjuvants mediated protection against Gag-expressing Listeria monocytogenes or vaccinia viral infections. Poly I:C and ISCOMs can alter antigen uptake and/or processing and we therefore used fluorescently labeled HIV Gag and DQ-OVA to assess these mechanisms respectively in multiple DC subsets. Poly I:C promoted uptake and retention of antigen, while ISCOMs enhanced antigen degradation. Combining Poly I:C and ISCOMs caused substantial death of DCs but persistence of degraded antigen. These data illustrate how combining adjuvants, such as Poly I:C and ISCOMs that modulate antigen processing and have potent innate activity, can enhance the magnitude, quality and phenotype of T cell immunity.

Antigen expression determines adenoviral vaccine potency independent of IFN and STING signaling

“…vaccinia virus (52,53). During vaccination, the presence of type I IFN typically enhances induction of CD8 T cell responses, such as with the modified vaccinia virus Ankara, an attenuated viral vaccine (56), and with protein subunit vaccination, in which adjuvants that induce robust IFN increase Ag uptake, promote crosspresentation, and thereby enhance T cell immunity (22,57,58). In contrast, the data presented herein demonstrate that type I IFN signaling limits Ag expression with rAd vaccination and can limit the initial expansion of CD8 T cell responses.…”

“…For DC subset identification, both popliteal LNs were harvested and pooled from 10 mice for each EGFP-expressing rAd and processed and stained as described previously (22). Briefly, DCs were isolated by enzymatic digestion of dLNs and enriched by For leukocyte subset identification, dLNs were processed as above and then stained with a LN subsetting panel (LIVE/DEAD Fixable AquaBlue Viability Dye; Life Technologies), CD8-APC-Cy7 (clone 53-6.7; Biolegend), CD4-PerCP-Cy5.5 (clone RM4-5; BD Pharmingen), CD19-APC (clone 6D5; BD Pharmingen), B220-PE-Cy7 (clone RA3-6B2; BD Pharmingen), CD11c-PE (clone HL3; BD Pharmingen), CD11b-AF700 (clone M1/70; BioLegend), pan-NK-Pacific Blue (clone DX5; BioLegend), CD3-PE-Cy5 (clone 145-2C11; BD Pharmingen), Gr1-FITC (clone RB6-8C5; eBioscience), and F4-80-Biotin (clone BM8; eBioscience), followed by streptavidin-Qdot-655 (Life Technologies).…”

“…Gag-specific CD8 T cell responses were characterized in the spleen, blood, and lung using peptide-MHC I tetramer staining. Mice were then challenged with recombinant Listeria monocytogenes expressing Gag, as a CD8 T cell-dependent model of protection (9,22). rAd5 induced the most potent and protective CD8 T cell responses, followed by rAd28 and rAd35 ( Figure 2, A and B).…”

Advances in aluminum hydroxide-based adjuvant research and its mechanism

“…18 For instance, MF59 (Novartis Vaccines) is the first oil-in-water emulsion licensed for use as an adjuvant in humans and has been shown to enhance the host immune responses against homologous and heterologous inter-pandemic seasonal influenza viral vaccine strains in the elderly and other at-risk populations. [19][20][21][22][23][24][25] AS03 and AS04 produced by GSK, 26,27 CpG, 28,29 A c c e p t e d M a n u s c r i p t 5 and poly-I:C 30,31 based adjuvant formulations are currently being evaluated in clinical trials.…”

Toll-like receptor 3-induced immune response by poly(D,L-lactide-co-glycolide) nanoparticles for dendritic cell-based cancer immunotherapy

“…The potency of poly I:C has been demonstrated by its immunomodulatory effects in mice. [16][17][18] Poly I:C mimics viral double-stranded RNA, which is a promising immunostimulatory candidate for vaccines directed against intracellular pathogens. However, TLR3 is localized in the endosome of DCs.…”