Thermophobic Trehalose Glycopolymers as Smart C-Type Lectin Receptor Vaccine Adjuvants.

Herein we report the first synthetic vaccine adjuvants that attenuate potency in response to small, 1-2°C, changes in temperature about their Lower Critical Solution Temperature (LCST). Adjuvant additives significantly increase vaccine efficacy. However, adjuvants also cause inflammatory side-effects, such as pyrexia, which currently limits their use. To address this, we created a thermophobic vaccine adjuvant engineered to attenuate potency at temperatures correlating to pyrexia. Thermophobic adjuvants were synthesized by combining a rationally designed trehalose glycolipid vaccine adjuvant with thermoresponsive poly-N-isoporpylacrylamide (NIPAM) via Reversible Addition-Fragmentation Chain-Transfer polymerization. The resulting thermophobic adjuvants exhibited LCSTs near 37°C, and self-assembled into nanoparticles with temperature-dependent sizes (90-270 nm). Thermophobic adjuvants activated HEK-mMINCLE and other innate immune cell lines as well as primary mouse Bone Marrow-Derived Dendritic Cells and Macrophages. Inflammatory cytokine production was attenuated under conditions mimicking pyrexia (above the LCST) relative to homeostasis (37°C) or below the LCST. This thermophobic behavior correlated with decreased adjuvant R g observed by DLS, as well as glycolipid-NIPAM shielding interactions observed by NOESY-NMR. In-vivo, thermophobic adjuvants enhanced efficacy of a whole inactivated Influenza A/California/04/2009 virus vaccine, by increasing neutralizing antibody titers and CD4 + /44 + /62L + lung and lymph node central memory T cells, as well as providing better protection from morbidity after viral challenge relative to unadjuvanted control vaccine. Together, these results demonstrate the first adjuvants with potency regulated by temperature. We envision that with further investigation, this approach could enhance vaccine efficacy while maintaining safety. This article is protected by copyright. All rights reserved.