Dissecting innate immune mechanisms to support biomarkers discovery and to increase efficacy of vaccines against fentanyl toxicity 3965

Abstract Description With over 100,000 fatal overdoses yearly and 6 million cases of opioid use disorder in 2022, the U.S. opioid epidemic is a public health burden that urges action. Anti-opioid vaccines offer a promising approach to help curb this crisis. To foster vaccine translation, this study tested second generation adjuvants and explored predictive biomarkers of efficacy. Results demonstrated that a Toll Like Receptor (TLR) 7/8 agonist significantly enhanced the efficacy of a lead anti-fentanyl vaccine in blocking fentanyl-induced effects in rodents. Data showed that TLR7/8 activation combined with alum salts boost fentanyl-specific B cell responses in mice by modulating the recruitment and activation status of innate immune cell subsets at the injection site and its draining lymph nodes. Single-cell B cell receptor (BCR) sequencing offers evidence that TLR7/8 induces a distinct BCR repertoire. Results further suggest CD40 and CD86 expression levels on antigen presenting cells (APCs) within 24hrs of injection as early predictors of vaccine efficacy. To elucidate cellular and molecular mechanisms of TLR7/8 efficacy, and to evaluate the potential for translating these preclinical biomarkers into clinical uses, an in vitro screening strategy used human whole blood to profile the activation status of APCs via flow cytometry and cytokines via a multiplexed assay. Mouse and human data support using these biomarkers and TLR7/8 agonists in enhancing vaccine efficacy against fentanyl. Funding Sources This work was supported by NIH under UG3/UH3 DA048386 (PI Marco Pravetoni), and NIDA/NRSA Grant Number: 1F31DA059235-01 (PI Fatima Hamid). Topic Categories Vaccines and Immunotherapy (VAC)