Deciphering immunological mechanisms underlying the efficacy of nanoparticle-based vaccines against opioid use disorder (OUD)

Abstract The highly complex OUD and overdose epidemic poses a huge public health and economic burden, urging the need for safe and more effective therapeutic options. Vaccines offer a promising strategy for OUD treatment and prevention of overdose. Vaccinating against opioids generates drug-specific polyclonal antibodies (Ab) that selectively bind targeted opioids, blocking their distribution to the brain and thus blunting opioid induced rewards, pharmacological and side effects. Previous clinical trials of addiction vaccines showed proof of efficacy only in subjects with the highest Ab titers, highlighting the need to design more effective vaccines. The generation of a robust anti-drug polyclonal Abs response relies on CD4+ T cell-dependent B cell activation, hence dendritic cells (DC) are crucial for initiating CD4+ T cells priming and B cell responses. To improve vaccine formulation, we are exploiting a lipid-polymer hybrid nanoparticle (LPNP) platform and toll-like receptor (TLR) agonists to potentiate antigen recognition by antigen presenting cells (APCs) and subsequently the efficacy of anti-opioid conjugate vaccines. Using a flow cytometry-based in vitro activation assay, we demonstrated that LPNP-based vaccines are more effective in inducing macrophages activation marker (iNOS) and DCs co-stimulatory molecules and maturation markers (CD86, CD40, and MHC II) compared to conventional vaccines. Adding selected TLR agonists further improved nanovaccine efficacy in inducing the maturation and activation of APCs. These findings were confirmed with RT-qPCR quantifying mRNA expression of above-mentioned markers. These studies will identify key APCs subsets contributing to vaccine efficacy against OUD and other targets. Supported by grants from NIH (UG3/UH3 DA048775)