Carbomer-based adjuvant elicits CD8 T-cell immunity by inducing a distinct metabolic state in cross-presenting dendritic cells

Abstract

There is a critical need for adjuvants that can safely elicit potent and durable T cell-based immunity to intracellular pathogens. Here, we report that parenteral vaccination with a carbomer-based adjuvant, Adjuplex (ADJ), stimulated robust CD8 T-cell responses to subunit antigens and afforded effective immunity against respiratory challenge with a virus and a systemic intracellular bacterial infection. Studies to understand the metabolic and molecular basis for ADJ’s effect on antigen cross-presentation by dendritic cells (DCs) revealed several unique and distinctive mechanisms. ADJ-stimulated DCs produced IL-1β and IL-18, suggestive of inflammasome activation, but in vivo activation of CD8 T cells was unaffected in caspase 1-deficient mice. Cross-presentation induced by TLR agonists requires a critical switch to anabolic metabolism, but ADJ enhanced cross presentation without this metabolic switch in DCs. Instead, ADJ induced in DCs, an unique metabolic state, typified by dampened oxidative phosphorylation and basal levels of glycolysis. In the absence of increased glycolytic flux, ADJ modulated multiple steps in the cytosolic pathway of cross-presentation by enabling accumulation of degraded antigen, reducing endosomal acidity and promoting antigen localization to early endosomes. Further, by increasing ROS production and lipid peroxidation, ADJ promoted antigen escape from endosomes to the cytosol for degradation by proteasomes into peptides for MHC I loading by TAP-dependent pathways. Furthermore, we found that induction of lipid bodies (LBs) and alterations in LB composition mediated by ADJ were also critical for DC cross-presentation. Collectively, our model challenges the prevailing metabolic paradigm by suggesting that DCs can perform effective DC cross-presentation, independent of glycolysis to induce robust T cell-dependent protective immunity to intracellular pathogens. These findings have strong implications in the rational development of safe and effective immune adjuvants to potentiate robust T-cell based immunity.

Vaccine-induced systemic and mucosal T cell immunity to SARS-CoV-2 viral variants

“…Unlike T RM -centric protection against IAV, either mucosal or parenteral vaccinations protect against the β-variant of SARS-CoV-2, which suggest that both T RM s and systemic migratory memory T cells can protect against SARS-CoV-2. Likewise, systemic migratory T cell memory controls mucosal challenge with vaccinia virus ( 40 ). Taken together, these findings highlight the differences in tenets of T cell–dependent protective immunity to respiratory infections with viruses, such as influenza virus, SARS-CoV-2, and poxvirus, and demonstrate the relative importance of antibodies and T cells in immune prophylaxis against SARS-CoV-2 variants.…”

Multi-Omic Single-Shot Technology for Integrated Proteome and Lipidome Analysis

“…For lipidomics, raw data files were processed using Compound Discoverer 2.1 (Thermo Scientific) and Lipidex . The parameters were mainly adapted from previous literature. − Lipid retention time range was set to 60.1–89.0 min (0.5 min tolerance) and the precursor mass range was set to 100–5000 Da (10 ppm mass tolerance) for aggregation of chromatographic peaks into distinct compound groups. Peak detection required a signal-to-noise ratio of 1.5, a minimum peak intensity of 5 × 10 5 , and a maximum peak width of 0.75 min.…”

Vaccine adjuvants to engage the cross-presentation pathway

“…Interestingly, subcutaneous and intranasal vaccination generated systemic and mucosal T cell memory respectively, but only mucosal T cell memory elicited by intranasal vaccination protected against influenza virus. Other studies from our group demonstrated that ADJ robustly stimulates systemic antigen-specific CD4 and CD8 T-cell responses to subunit protein antigen, and protected against vaccinia virus, Listeria monocytogenes (L. monocytogenes ) and respiratory fungal infections ( 221 , 223 , 234 ). Specifically, upon subcutaneous vaccination of mice, ADJ elicited effector CD8 T cells that differentiated into a distinct subset of granzyme B-expressing CD27 LO ‘effector-like’ memory CD8 T cells, which provided highly effective immunity to intracellular bacteria L. monocytogenes in spleen and liver ( 222 ).…”