Heider, Robin M.

Abstract Opioid use disorder (OUD) affects over 40 million people worldwide, creating significant social and economic burdens. Medication for opioid use disorder (MOUD) is often considered the primary treatment approach for OUD. MOUD, including methadone, buprenorphine, and naltrexone, is effective for some, but its benefits may be limited by poor adherence to treatment recommendations. Immunopharmacotherapy offers an innovative approach by using vaccines to generate antibodies that neutralize opioids, blocking them from crossing the blood-brain barrier and reducing their psychoactive effects. To date, only 3 clinical trials for opioid vaccines have been published. While these studies demonstrated the potential of opioid vaccines for relapse prevention, there is currently no standardized protocol for evaluating their effectiveness. We have reviewed recent preclinical studies that demonstrated the efficacy of vaccines targeting opioids, including heroin, morphine, oxycodone, hydrocodone, and fentanyl. These studies showed that vaccines against opioids reduced drug reinforcement, decreased opioid-induced antinociception, and increased survival rates against lethal opioid doses. These studies also demonstrated the importance of vaccine formulation and the use of adjuvants in enhancing antibody production and specificity. Finally, we highlighted the strengths and concerns associated with the opioid vaccine treatment, including ethical considerations.

We previously reported the in vitro selection and characterization of a DNA aptamer capable of stimulating remyelination in a mouse model of multiple sclerosis. This aptamer was selected for its ability to bind to suspensions of crude murine myelin in vitro . Our initial studies in vitro and in vivo involved a 40-nucleotide derivative (LJM-3064) of the original 100-nucleotide aptamer. LJM-3064 retained robust myelin-binding properties. Structural characterization of LJM-3064 revealed that the guanosine-rich 5′ half of the sequence forms different G-quadruplex-type structures that are variably stable in the presence of physiologically relevant ions. We hypothesized that this structured domain is sufficient for myelin binding. In this study, we confirm that a 20-nucleotide DNA, corresponding to the 5′ half of LJM-3064, retains myelin-binding properties. We then optimize this minimal myelin-binding aptamer via systematic evolution of ligands by exponential enrichment after sparse rerandomization. We report a sequence variant (LJM-5708) of the 20-nucleotide myelin-binding aptamer with enhanced myelin-binding properties and the ability to bind cultured human oligodendroglioma cells in vitro , providing the first evidence of cross-species reactivity of this myelin-binding aptamer. As our formulation of DNA aptamers for in vivo remyelination therapy involves conjugation to streptavidin, we verified that the myelin-binding properties of LJM-5708 were retained in conjugates to avidin, streptavidin, and neutravidin. DNA aptamer LJM-5708 is a lead for further preclinical development of remyelinating aptamer technologies.